World War I, also known as the First World War, the Great War, the War of the Nations, and the "War to End All Wars", was a world conflict occurring from 1914 to 1918. No previous conflict had mobilized so many soldiers or involved so many in the field of battle. Never before had casualties been so high. Chemical weapons were used for the first time, the first mass bombardment of civilians from the sky was executed, and some of the century's first large-scale civilian massacres took place. Four dynasties, the Habsburgs, the Romanovs, the Ottomans and the Hohenzollerns, who had roots of power back to the days of the Crusades, all fell after the war.

World War I proved to be the decisive break with the old world order, marking the final demise of absolutist monarchy in Europe. It would prove the catalyst for the Russian Revolution, which would inspire later revolutions in countries as diverse as China and Cuba, and would lay the basis for the Cold War standoff between the Soviet Union and the United States. The defeat of Germany in the war and failure to resolve the unsettled issues that had caused the Great War would lay the basis for the rise of Nazism, and thus the outbreak of World War II in 1939. It also laid the basis for a new form of warfare that relied heavily on technology, and would involve non-combatants in war as never before.

It was commonly called "The Great War" or sometimes "the war to end all wars" until World War II, although the name "First World War" was coined as early as 1920 by Lt-Col à Court Repington in The First World War 1914–18. Some scholars write of the First World War as merely the first phase of a 30-year-long war spanning the period 1914–1945.

World War I became infamous for trench warfare, where huge numbers of troops were confined to trenches and could move little because of tight defenses. This was especially true of the Western Front. Over 9 million men would die on the battlefield, and nearly that many more people would die on the homefront from food shortages, starvation, genocide, and being caught up in the fighting.

Diplomatic and political origins

See: Causes of World War I and Participants in World War I

On June 28, 1914, Franz Ferdinand, Archduke of Austria and heir to the Austro-Hungarian throne, was assassinated in Sarajevo by Gavrilo Princip, a Bosnian Serb student. Though World War I was triggered by this assassination, the war's origins lie further back, in the complex web of alliances and counterbalances that developed between the various European powers over the course of the nineteenth century, following the final 1815 defeat of Napoleon Bonaparte at Waterloo. Napoleon's rise to power was, in turn, a direct consequence of the 1789 French Revolution, which overthrew the French monarchy.

Outbreak of war

Austrian regional security concerns grew with the near-doubling of neighbouring Serbia's territory as a result of the Balkan Wars of 1912-1913. Many in the Austrian leadership, not least Habsburg Emperor Franz Joseph, and Conrad von Hötzendorf, worried about Serbian nationalist agitation in the southern provinces of the Empire; they were still haunted by the memories of the Piedmontese inspired campaigns against the Austrian Italian provinces in 1859. Just as France had backed Piedmont in the campaign, culminating in the Battle of Solferino, they worried that Russia would back Serbia to annex Slavic areas of Austria. The feeling was that it was better to destroy Serbia before they were given the opportunity to launch a campaign.

Some members of the Austrian government also felt that a campaign in Serbia would be the perfect remedy to the internal political problems of the Empire. Many of them were frustrated by the power of the Hungarian government in the Empire. In 1914 the government of the Austro-Hungarian Empire had a "dualistic" structure. Austria and Hungary had essentially separate governments under one monarch. The Austrian government retained control over foreign policy, but was still dependent on the Hungarians for such things as budgetary approval. Often the Hungarian leadership, under István Tisza refused Austrian requests for things such as increased military spending. In hopes of ending the political gridlock that this caused, many hoped to form a federation, or at least triadic monarchy. The solution was seen in increasing the numbers of Slavs in the Empire to balance the Magyar population.

Franz Ferdinand's assassination in June 1914 provided the opportunity sought by some Austrian leaders for a reckoning with the smaller Slav kingdom. The Sarajevo conspirators were alleged by the Austro-Hungarian authorities to have been armed by the Black Hand, a pan-Serb nationalist grouping with alleged links to Serbian ruling circles. These links have proven to be somewhat dubious since then. In fact, Serbian government officials were eager not to antagonize their stronger northern neighbour and had ordered border officials to ensure Serbian radicals could not enter Bosnia or other portions of Austria-Hungary. However, since they were looking for an excuse for war, these considerations mattered little to Austro-Hungarian politicians.

With German backing, Austria-Hungary, acting primarily under the influence of Foreign Affairs Minister Leopold von Berchtold, sent an effectively unfulfillable 10-point ultimatum to Serbia (July 23, 1914), to be accepted within 48 hours.

Austria-Hungary demanded that the Serbian government undertake the following:

1. To suppress any publication which incites to hatred and contempt of the [Austrian] Monarchy . . .
2. To dissolve immediately the society styled Narodna Odbrana..and to proceed in the same manner against the other societies . . which engage in propaganda against [Austria]
3. To eliminate without delay from public instruction in Serbia, both as regards the teaching body and the methods of instruction, all that serves or might serve to foment the propaganda against Austria-Hungary
4. To remove from the military service and the administration in general all officers guilty of propaganda against [Austria--names to be given over by the Austrian govt.]
5. To accept the collaboration in Serbia of organs of [A-H govt.] in the suppression of the subversive movement directed against the territorial integrity of the Monarchy
6. To take judicial proceedings against the accessories to the plot of 28 June who are on Serbian territory; Organs delegated by [A-H] will take part in the investigations relating thereto
7. To proceed without delay to the arrest of [two named persons implicated according to the preliminary investigation undertaken by Austria]
8. To prevent by effective measures the cooperation of [Serbia] in the illicit traffic in arms and explosives across the frontier . . . .
9. To furnish [Austria] with explanations regarding the unjustifiable utterances of high Serbian officials both in Serbia and abroad, who . . . have not hesitated since the outrage of 28 June to express themselves . . in terms of hostility towards [Austria]
10. To notify [Austria] without delay of the execution of the[se] measures . . .

The Serbian government agreed to all but one of the demands, noting that participation in its judicial proceedings by a foreign power would violate its constitution. Austria-Hungary nonetheless broke off diplomatic relations (July 25) and declared war (July 28) through a telegram sent to the Serbian government.

The Russian government, which had pledged in 1909 to uphold Serbian independence in return for Serbia's acceptance of the Bosnia annexation, mobilized its military reserves on July 30 following a breakdown in crucial telegram communications between Wilhelm and Tsar Nicholas II (the famous "Willy and Nicky" correspondence), who was under pressure by his military staff to prepare for war. Germany demanded (July 31) that Russia stand down her forces, but the Russian government persisted, as demobilization would have made it impossible to re-activate its military schedule in the short term. Germany declared war against Russia on August 1 and, two days later, against the latter's ally France.

The outbreak of the conflict is often attributed to the alliances established over the previous decades — Germany-Austria-Italy vs. France-Russia; Britain and Serbia being aligned with the latter. In fact, none of the alliances were activated in the initial outbreak, though Russian general mobilization and Germany's declaration of war against France were motivated by fear of the opposing alliance being brought into play.

Britain's declaration of war against Germany (August 4) was officially the result not of her understandings with France and Russia (Britain was technically allied to neither power), but of Germany's invasion of Belgium on August 4, 1914, whose independence Britain had guaranteed to uphold in the Treaty of London of 1839, and which stood astride the planned German route for invasion of Russia's ally France. Unofficially, it was already generally accepted in government that Britain could not remain neutral, since without the co-operation of France and Russia her colonies in Africa and India would be under threat, while German occupation of the French Atlantic ports would be an even larger threat to British trade as a whole.

Responsibility

Many different hypotheses have been proposed to explain who is to blame for the outbreak of the First World War. Early explanations, prominent in the 1920s and 1930s, stressed the rigidity of the alliance system and the nature of secret diplomacy, a contention that implied that responsibility for the war's outbreak was shared equally among the powers. The rigidity of French, German, Austrian and Russian military planning factored heavily. The military doctrine of all of these nations was emphatic that victory would only be gained by striking first, and that mobilization, once begun, could not be halted or slowed without risking invasion and defeat. The civilian leaders of the European powers therefore found themselves with ever fewer options and little room to maneuver, as the last weeks of July 1914 slipped away. Frantic diplomatic efforts to mediate the Austrian-Serbian quarrel simply became irrelevant in the end, as the automatic military escalations between Germany and Russia reinforced one another.

The Fischer-Geise theory, proposed by Fritz Fischer and Immanuel Geise in the 1960s, places most blame upon Germany. Most recent scholarship largely echoes this: David Fromkin, in Europe's Last Summer, published in 2004, blames Germany and Austria-Hungary entirely, stating bluntly that "Austria-Hungary started its local war with Serbia, whilst Germany's military leaders started the worldwide war against France and Russia." Some other theories emphasize Britain's desire to join the war in order to stop Germany from increasing its political and economic power, although there is little documentary evidence to prove this. Furthermore, Niall Ferguson, in The Pity of War, published in 1998, argues that Britain went to war with Germany because it perceived it as being weak, and not strong.

A definitive answer eludes historians to this day.

Opening battles

Some of the very first actions of the war occurred far from Europe, including Africa and the Pacific Ocean. On August 8, 1914 the German protectorate of Togoland was invaded by a combined French and British force. On August 10, German forces based in South-West Africa attacked South Africa, and on August 11, Australian forces landed on the island of Neu-Pommern, which was part of German New Guinea. Within several months German forces in the Pacific had surrendered, or had been driven out, whereas sporadic and often fierce fighting continued in Africa for the remainder of the war.

In Europe, Germany and Austria-Hungary suffered from miscommunication regarding each army's intentions. Germany had originally guaranteed to support Austria-Hungary's invasion of Serbia, but the interpretations of this idea differed. Austro-Hungarian leaders thought that Germany would cover their northern flank against Russia, but Germany had planned for Austria-Hungary to focus the majority of its troops on Russia, while Germany dealt with France on the Western Front. This confusion forced the Austro-Hungarian army to split its troop concentrations from the south in order to meet the Russians in the north. The Serb army, which was coming up from the south of the country, met the Austrian army at Cer on August 12 1914.

The Serbians were set up in defensive positions against the Austrians. The first attack came on August 16th, between parts of the 21st Austro-Hungarian division and parts of the Serbian Combined division. In harsh night-time fighting, the battle ebbed and flowed, until the Serbian line was rallied under the leadership of Stepa Stepanovic. Three days later the Austrians retreated across the Danube, having suffered 21,000 casualties against 16,000 Serbian casualties. This marked the first allied victory of the war. The Austrians had not achieved their main goal of eliminating Serbia, and it became increasingly likely that Germany would be forced to maintain forces on both fronts.

Germany's plan (named the Schlieffen plan) to deal with the Franco-Russian alliance involved delivering a knock-out blow to the French and then turning to deal with the more slowly mobilized Russian army. Rather than attack France directly, it was deemed prudent to attack France from the north. To do so, the German army had to march through Belgium. Germany demanded this free passage from the Belgian government, promising that Belgium would be Germany's firm ally if this was agreed to. When Belgium refused, Germany invaded and began marching through Belgium anyway, after first invading and securing tiny Luxembourg. It soon encountered resistance before the forts of the Belgian city of Liège. Britain sent an army to France, which advanced into Belgium.

The delays brought about by the resistance of the Belgian, French and British forces and the unexpectedly rapid mobilization of the Russians upset the German plans. Russia attacked in East Prussia, diverting German forces intended for the Western Front. Germany defeated Russia in a series of battles collectively known as the (second) Battle of Tannenberg, but this diversion allowed French and British forces to finally halt the German advance on Paris at the First Battle of the Marne (September 1914) as the Central Powers were forced into fighting a war on two fronts.

Southern theatres

Entry of the Ottoman Empire

The Ottoman Empire joined the Central Powers in October–November 1914, threatening Russia's Caucasian territories and Britain's communications with India and the East via the Suez canal. British action opened another front in the South with the Gallipoli (1915) and Mesopotamia campaigns, though initially the Turks were successful in repelling enemy incursion. But in Mesopotamia, after the disastrous Siege of Kut (1915–16), the British reorganized and captured Baghdad in March 1917. Further to the west in Palestine, initial British failures were overcome with Jerusalem being captured in December 1917 and the Egyptian Expeditionary Force under Edmund Allenby going on to break the Ottoman forces at the Battle of Megiddo (September 1918).

Russian armies generally had the best of it in the Caucasus. Enver Pasha, supreme commander of the Turkish armed forces, was a very ambitious man, with a dream to conquer central Asia. He was not a practical soldier. He launched an offensive with 100,000 troops against the Russians in the Caucasus in December of 1914. Insisting on a frontal attack against Russian positions in the mountains in the heart of winter, Enver lost 86% of his force. A new Russian commander on the front in the fall of 1915, Grand Duke Nicholas, brought new vigor. A major offensive in 1916 drove the Turks out of much of present-day Armenia, and Armenian guerrilla support to Russian armies resulted in the deportation of Armenian population in eastern Anatolia to Syria and other territories under Istanbul's control. With control of part of the southern Black Sea coast, Nicholas pushed forward the construction of railway lines to bring up supplies. He was ready for an offensive in the spring of 1917. If it had gone ahead, there was a very good chance that Turkey would have been knocked out of the war in the summer of 1917. But, because of the Russian Revolution, Grand Duke Nicholas was recalled and the Russian armies soon fell apart.

Italian participation

Italy had been nominally allied to the German and Austro-Hungarian Empires since 1882, but had her own designs against Austrian territory in the South Tyrol, Istria and Dalmatia, and a secret 1902 understanding with France effectively nullifying her alliance commitments. Italy refused to join Germany and Austria-Hungary at the beginning of the war and joined the Entente by signing the London Pact in April and declaring war on Austria-Hungary in May 1915; it declared war against Germany fifteen months later.

In general, the Italians enjoyed numerical superiority, but were poorly equipped; instead, the Austro-Hungarian defense took advantage of the mostly mountainous terrain. So, the 1915 Italian offensives on the Soča (Isonzo) front (the part of the border which was closest to Trieste, a major Italian objective) were repelled. The Austro-Hungarians counter-attacked from the South Tyrol in the spring of 1916 (Strafexpedition), but they made little progress. In the summer, the Italians took back the initiative, capturing the town of Gorizia. After this minor victory, the front remained practically stable for over one year, despite several Italian offensives. In the fall of 1917, thanks to the improving situation on the Eastern front, the Austrians received large reinforcements, including German assault troops. On October 26, they launched a crushing offensive that resulted in the victory of Kobarid (Caporetto): the Italian army was initially routed, but after retreating more than 100 km, it was able to reorganize and hold ground at the Battle of the Piave River. In 1918 the Austrians repeatedly failed to break this Italian line, and surrendered to the Entente powers in November.

Throughout the war Austro-Hungarian Chief of Staff, Conrad von Hötzendorf had a deep hatred for the Italians because he had always perceived them to be the greatest threat to his state. Their betrayal in 1914 enraged him even further. His hatred for Italy blinded him in many ways, and he made many foolish tactical and strategic errors during the campaigns in Italy.

Fall of Serbia

After repelling three Austrian invasions in August-December 1914, Serbia fell to combined German, Austrian and Bulgarian invasion in October 1915. Serbian troops continued to hold out in Albania and Greece, where a Franco-British force had landed to offer assistance and to pressure the Greek government into war against the Central Powers.

Early stages: from romanticism to the trenches

The perception of war in 1914 was almost romantic, and its declaration was met with great enthusiasm by many people. The common view was that it would be a short war of manoeuvre with a few sharp actions (to "teach the enemy a lesson") and would end with a victorious entry into the capital (the enemy capital, naturally) then home for a victory parade or two and back to "normal" life. There were some pessimists (like Lord Kitchener) who predicted the war would be a long haul, but "everyone knew" the War would be "Over by Christmas...."

It has been proposed that the excitement the war caused with German youths helped to pave the way toward a militaristic and fascist mindset that made it possible for the Nazi party to take control of Germany decades later when these youths had become adults.

See also: Recruitment to the British Army during WW I

Trench warfare begins

After their initial success on the Marne, Entente and German forces began a series of outflanking manoeuvres to try to force the other to retreat, in the so-called Race to the Sea. Britain and France soon found themselves facing entrenched German positions from Lorraine to Belgium's Flemish coast. The sides took set positions, the British and French seeking to take the offensive while Germany sought to defend the territories they had occupied. One consequence of this was that the German trenches were much better constructed than those of their enemy: the Anglo-French trenches were only intended to be 'temporary' before their forces broke through the German defences. Neither side proved able to deliver a decisive blow for the next four years, though protracted German action at Verdun (1916) and Allied failure the following spring brought the French army to the brink of collapse. Futile attempts at more frontal assaults, at terrible cost to the French poilu infantry, led to mutinies which threatened the integrity of the front line.

Around 800,000 soldiers from Britain and the Empire were on the Western Front at any one time, 1,000 battalions each occupying a sector of the line from Belgium to the Arne and operating a month-long four stage system, unless an offensive was underway. The front contained over 6,000 miles of trenches. Each battalion held its sector for around a week before moving back to support lines and then the reserve lines before a week out-of-line, often in the Poperinge or Amiens areas.

The Eastern Front and Russia

While the Western Front had reached stalemate in the trenches, the war continued to the east.

See also: Eastern Front (World War I)

German victories in the East

The Russian initial plans for war had called for simultaneous invasions of Austrian Galicia and German East Prussia. Although Russia's initial advance into Galicia was largely successful, they were driven back from East Prussia by the victories of the German generals Hindenburg and Ludendorff at Tannenberg and the Masurian Lakes in August and September 1914. Russia's less-developed economic and military organisation soon proved unequal to the combined might of the German and Austro-Hungarian Empires. In the spring of 1915 the Russians were driven back in Galicia, and in May the Central Powers achieved a remarkable breakthrough on Poland's southern fringes, capturing Warsaw on August 5 and forcing the Russians to withdraw from all of Poland.

Russia unsettled

Dissatisfaction with the Russian government's conduct of the war grew despite the success of the June 1916 Brusilov offensive in eastern Galicia against the Austrians, when Russian success was undermined by the reluctance of other generals to commit their forces in support of the victorious sector commander. Allied fortunes revived only temporarily with Romania's entry into the war on August 27: German forces came to the aid of embattled Austrian units in Transylvania, and Bucharest fell to the Central Powers on December 6. Meanwhile, internal unrest grew in Russia, as the Tsar remained out of touch at the front, while Empress Alexandra's increasingly incompetent rule drew protests from all segments of Russian political life, resulting in the murder of Alexandra's favourite Rasputin by conservative noblemen at the end of 1916.

The Russian Revolution

In March 1917, demonstrations in St. Petersburg culminated in the abdication of Tsar Nicholas II and the appointment of a weak centrist Provisional Government, which shared power with the socialists of the Petrograd Soviet. This division of power led to confusion and chaos, both on the front and at home, and the army became progressively less able to effectively resist Germany. Meanwhile, the war, and the government, became more and more unpopular, and the discontent was used strategically by the Bolshevik party, led by Vladimir Lenin, in order to gain power.

The triumph of the Bolsheviks in November was followed in December by an armistice and negotiations with Germany. At first, the Bolsheviks refused to agree to the harsh German terms, but when Germany resumed the war and marched with impunity across Ukraine, the new government acceded to the Treaty of Brest-Litovsk on March 3, 1918, which took Russia out of the war and ceded vast territories including Finland, the Baltic provinces, Poland and Ukraine to the Central Powers.

After the Russians initially dropped out of the war, the Allies led a small-scale invasion of Russia. The invasion was made with intent to punish the Russians for dropping out of World War I and to support the Czarists in the Russian Revolution. Troops landed in Archangel and in another city on the Pacific coast of Russia. The bulk of the troops were from Michigan, a northern state in the United States. The Allied forces were initially told they were invading to defend supplies from German troops. In reality, they were defending them from communist Russians. A memorial commemorating the event is located in White Chapel Cemetery in Troy, Michigan. The force also included a number of Canadians who were based in Vladivostok. The Canadian force contained an artillery unit, but they saw minimal combat.

Societal effects

One of the distinguishing features of the war was its totality. All aspects of the societies fighting were affected by the conflict, often causing profound societal change, even if the countries were not in the warzone.

One of the most dramatic such effects was the expansion of government, its powers and responsibilities in Britain, France, the United States, and the British dominions. In order to harness all the power of their societies, new government ministries and powers were created. New taxes were levied, and laws enacted, all designed to bolster the war effort, many of which have lasted to this day.

At the same time, the war strained the abilities of the formerly large and bureaucratized governments such as in Austria-Hungary and Germany. Here, however, the long term effects were clouded by the defeat of these governments.

Families were altered by the departure of many men. With the death or absence of the primary wage earner women were forced into the workforce in unprecedented numbers, at least in many of the Entente powers. At the same time, industry needed to replace the lost labourers sent to war. This aided the struggle for voting rights for women.

Turning the tide

Events of 1917 would prove decisive in ending the war, although their effects would not fully be felt until 1918. The Allied naval blockade of Germany began to have serious impact on morale and productivity on the German home-front. In response, in February 1917, the German General Staff (OHL) were able to convince Chancellor Theobald von Bethmann-Hollweg to declare unrestricted submarine warfare, with the goal of starving Britain out of the war. Tonnage sunk rose above 500,000 tonnes per month from February until July, peaking at 860,000 tonnes in April. After July, the newly introduced convoy system was extremely effective in neutralising the U-boat threat. Britain was safe from the threat of starvation. Even more importantly, April 1917 finally saw the formal entry of the United States into the war, in response to the sinking of the Lusitania, on May 17, 1915.

Indicator Nets were predominantly deployed by the British Royal Navy as a means—albeit generally unsuccessful—of discouraging enemy (usually German) submarines from entering Allied waters. Constructed using light steel nets these were anchored at various depths to the sea bed around key Allied naval bases and were intended to entangle enemy U-boat traffic, although even then submarines were often able to disentangle themselves and escape before they were blown up by depth charges. They were seldom used as the sole anti-submarine measure but were instead mixed with other defences, which usually included extensive minefields and patrolling warships. In time mines were actually attached to the nets, thereby reducing the survival chances of an entangled submarine.

Once a submarine became entangled a marker buoy attached to the net would drift along the surface indicating enemy activity below. The first example of indicator nets assisting in the destruction of a German U-boat occurred at Dover when the U-8 became entangled on 4 March 1915.

Indicator Nets were used extensively—dropped from light fishing craft—at both Dover and Otranto Barrages. Individual nets were sometimes as much as 100 metres in length. While these were ultimately of some benefit at Dover (where the barrage was constantly fine-tuned to produce results) they proved ineffective at Otranto, with gaps between the light steel nets sufficiently wide to allow enemy submarines through. Under cover of darkness, U-boats could also thwart the nets by coasting along the surface, as happened at the Otranto Barrage.

The decisive victory of Germany at the Battle of Caporetto led to the Allied decision at the Rapallo Conference to form the Supreme Allied Council at Versailles to co-ordinate plans and action.

In December, the Central Powers signed an Armistice with Russia, thereby releasing troops from the eastern front for use in the west. With both German reinforcements and new American troops pouring into the Western Front, the final outcome of the war was to be decided in that front. The Central Powers knew that they could not win a protracted war now that American forces were certain to be arriving in increasing numbers, but held high hopes for a rapid offensive in the West, using their reinforced troops and new infantry tactics. Furthermore, rulers of both the Central Powers and the Entente began to recognize the threat first raised by Ivan Bloch in 1899, that protracted industrialized war threatened social collapse and revolution throughout Europe. Both sides urgently sought a decisive, rapid victory on the Western Front.

Entry of the United States

A long stretch of American isolationism left the United States reluctant to involve itself with what was popularly conceived as a European dispute.

Early in 1917 Germany resumed its policy of unrestricted submarine warfare. This, combined with public indignation over the Zimmerman telegram, led to a final break of relations with the Central Powers. President Woodrow Wilson requested that the U.S. Congress declare war, which it did on April 6, 1917 (see: Woodrow Wilson declares war on Germany on Wikisource). The Senate approved the war resolution 82-6, the House with 373-50.

Although the American contribution to the war was important, particularly in terms of the threat posed by increased US presence in Europe, the United States was never formally a member of the Allies, but an "Associated Power".

The United States Army and the National Guard had mobilized in 1916 to pursue the Mexican "bandit" Pancho Villa, which helped speed up the mobilization. The United States Navy was able to send a battleship group to Scapa Flow to join with the British Grand Fleet, and a number of destroyers to Queenstown, Ireland, to help guard convoys. However, it would be some time before the United States forces would be able to contribute significant manpower to the Western and Italian fronts.

The British and French insisted that the United States emphasize sending infantry to reinforce the line. Throughout the war, the American forces were short of their own artillery, aviation, and engineering units. However, General John J. Pershing, American Expeditionary Force commander, resisted breaking up American units and using them as reinforcements for British and French units, as suggested by the Allies.

The reasons the United States got involved in the war are numerous and much-debated. In 1934, the US government created the Nye Committee to investigate the matter. In 1936, the committee reported that between 1915 and April 1917, the US loaned Germany 27 million dollars ($27,000,000, or $470,000,000 adjusted for inflation in 2005 dollars). In the same period, the US loaned Britain and its allies 2.3 billion dollars ($2,300,000,000 or $40,000,000,000 adjusted for inflation in 2005 dollars), or about 85 times as much. They concluded that the US entered the war because it was in its commercial interest for Britain not to lose.

German Spring Offensive of 1918

Ludendorff made plans for a 1918 general offensive along the Western Front. The Spring Offensive sought to divide the British and French armies in a series of feints and advances. To the German leadership, a deterioriating economic and manpower situation compared to the Allies' strengthening through the United States' entry made 1918 the last chance for victory. German strength in the West was additionally boosted by the recent transfer of divisions from the Eastern Front.

Operation Michael opened on 21 March 1918 with an attack against the British towards the rail junction at Amiens. It was Ludendorff's intention to split the British and French armies at this point. German forces achieved an unprecedented advance of 60km. For the first time since 1914, maneuver had returned to the battlefield.

British and French trenches were defeated using novel infiltration tactics. To this time, attacks had been characterized by long artillery bombardments and continuous-front mass assaults. However, in the Spring Offensive the German Army used artillery briefly and infiltrated small groups of infantry at weak points, attacking command and logistics areas and surrounding points of serious resistance. These isolated positions were then destroyed by more heavily armed infantry. German success relied greatly on this tactic.

The frontline had now moved to within 120 kilometres of Paris. Three super-heavy Krupp railway guns advanced to fire 183 shells on Paris, causing many Parisians to flee the city. The initial stages of the offensive were so successful that Wilhelm II declared March 24 a national holiday. Many Germans thought victory to be close. However, supply shortages and attrition caused the German offensive to halt. German casualties between March and April 1918 were 270,000.

United States divisions, which Pershing sought to field as an independent force, were assigned to depleted French and British commands on 28 March. A supreme command of Allied forces was created at the Doullers conference in which Field Marshal Douglas Haig handed control of his forces over to Ferdinand Foch.

Following Operation Michael, Germany launched Operation Georgette to the north against the Channel ports. This was halted with less significant territorial gains.

Operations Blucher and Yorck were then conducted by the German Army to the south, broadly towards Paris.

Operation Marne was then launched on 15 July as an attempt to encircle Reims, beginning the Second Battle of the Marne. The resulting Allied counter attack marked the first successful Allied offensive of the war. By July 20, 1918, the Germans were at their Kaiserschlacht starting lines. Following the last phase, the German Army never again held the initiative.

Meanwhile, Germany was crumbling internally as well. Anti-war marches were a frequent occurrence and morale within the army was at low levels. Industrial output had fallen 53% from 1913.

On August 8, 1918, the predicted counter-offensive occurred. It involved 414 tanks, and 120,000 men. The allies had advanced twelve kilometres into German territory in just seven hours. Erich Ludendorff referred to this day as "the blackest day for the German army in the history of the war".

Allied victory

However, after a few days the offensive had slowed down—the British had encountered problems with all but seven of their four hundred and fourteen tanks. On August 15, 1918, Haig called an end to the offensive and began to plan for an offensive in Albert. That offensive came on August 21. Some 130,000 American troops were involved, along with soldiers from British third and fourth armies. The offensive was an overwhelming success. The German second army had been pushed back over a fifty-five kilometre front. The town of Bapaume was captured on August 29 and by September 2, the Germans had been forced back to the Hindenburg Line.

The attempt to take the Hindenburg Line occurred on September 26 (known as the Meuse-Argone offensive): 260,000 American soldiers went "over the top" towards the Hindenburg Line. All divisions were successful in capturing their initial objectives, except the 79th division of the AEF. They met stiff resistance at Montfaucon and were unable to progress. This failure allowed the Germans to recover and regroup. Montfaucon was captured on September 27; however, failure to take it the day before proved to be one of the most costly mistakes of the entire campaign.

By the start of October it was evident that things were not going according to plan. Many tanks were once again breaking down, and those that were actually operable were rendered useless due to tank commanders finding the terrain impossible to navigate. Regardless of this, Ludendorff had decided by October 1 that Germany had two ways out—total annihilation or an armistice. He recommended the latter to senior figures at a summit in Spa, Belgium on that very same day. Pershing continued to pound the exhausted and bewildered Germans without relent for all of October along the Meuse-Argonne front. This would continue until the end of the war.

Meanwhile, news of Germany's impending defeat had spread throughout the German Armed forces. The threat of mutiny was rife. Naval commander Admiral Scheer and Ludendorff decided to launch a last ditch attempt to restore the "valour" of the German navy. He knew that any such action would be vetoed by the government of Max von Baden, so he made the decision not to inform him. Via word of mouth or otherwise, word of the impending assault reached sailors at Kiel. Many of the sailors took unofficial leave—refusing to be part of an offensive which they believed to be nothing more than a suicide bid. It was mostly Luderndorff who took the fall for this—the Kaiser dismissing him on October 26.

However, since the end of September 1918 Ludendorff had been concocting a plan of his own. Even although he was a traditionalist conservative, he decided to try and incite a political revolution by introducing new reforms that "democratized" Germany; also satisfying the monarchists as the Kaiser's reign would continue unabridged. He believed that democratization would show the German people that the government was prepared to change, thus reducing the chance of a socialist style revolt as was seen in Russia in 1917. However, it is the belief of some historians that by doing so Ludendorff had an ulterior motive. His reforms would hand more power over to the members of the Reichstag—particularly the ruling parties, at this time the centre party (under Matthias Erzberger), the liberals, and the social democrats. Therefore, with Luderndorff handing more power to these parties they would have the authority to request an armistice. With 5,989,758 Germans casualties (4,216,058 wounded, 1,773,700 killed), they did just that. Soon after that, Ludendorff had a dramatic change of heart—and began to claim that the very parties who he handed power to had lost Germany the war. These politicians had "stabbed Germany in the back". Prince Max von Baden (SDP) was put in charge. Negotiations for a peace were immediately put into place on his appointment. Also, he was torn between the idea of a constitutional monarchy or complete abolition. However, the matter was taken out of his hands by Philipp Scheidemann, who on November 9, 1918, declared Germany a Republic from a balcony atop the Reichstag. Von Baden announced that the Kaiser was to abdicate—before the Kaiser had himself made up his mind. Imperial Germany had died, and a new Germany had been born: the Weimar Republic.

End of the war

Bulgaria was the first of the Central Powers to sign an armistice (September 29, 1918). Germany requested a cease-fire on October 3, 1918. When Wilhelm II ordered the German High Seas Fleet to sortie against the Allied navies, they mutinied in Wilhelmshaven starting October 29, 1918. On October 30 the Ottoman Empire capitulated. On November 3 Austria-Hungary sent a flag of truce to the Italian Commander to ask an Armistice and terms of peace. The terms having been arranged by telegraph with the Allied Authorities in Paris, were communicated to the Austrian Commander, and were accepted. The Armistice with Austria was granted to take effect at three o'clock on the afternoon of November 4. Austria and Hungary had signed separate armistices following the overthrow of the Habsburg monarchy.

Following the outbreak of the German Revolution, a Republic was proclaimed on November 9, marking the end of the German Empire. The Kaiser fled the next day to the Netherlands, which granted him political asylum. (See Weimar Republic for details.) On November 11 Germany signed in a railroad car at Compiègne, in France, an armistice with the Allies. On the eleventh day of the eleventh month at the eleventh hour it was official, the war was over.

For data on military and civilian deaths by nationality, see World War I casualties.

Technology

The First World War was different from prior military conflicts: it was a meeting of 20th century technology with 19th century mentality and tactics. This time, millions of soldiers, both volunteers and conscripts fought on all sides with Kitchener's Army being a notable volunteer force.

Much of the war's combat involved trench warfare, where hundreds often died for each metre of land gained. Many of the deadliest battles in history occurred during the First World War. Such battles include Ypres, Vimy Ridge, Marne, Cambrai, Somme, Verdun, and Gallipoli. The combination of machine guns and barbed wire was responsible for the largest number of casualties during the First World War.

The First World War also saw the use of chemical warfare and aerial bombardment, both of which had been outlawed under the 1907 Hague Convention.

Chemical warfare was a major distinguishing factor of the war. Gases uses ranged from tear gas to disabling chemicals such as mustard gas and killing agents like phosgene. Only a small proportion of casualties were caused by gas, but it achieved harassment and psychological effects. Effective countermeasures to gas were found in gas masks and hence in the later stages of the war, as the use of gas increased, in many cases its effectiveness was diminished.

Fixed-wing aircraft were first used militarily during the First World War. Initial uses consisted principally of reconnaissance, though this developed into ground-attack and fighter duties as well. Strategic bombing aircraft were created principally by the German and British empires, though the former used Zeppelins to this end as well.

U-boats, or submarines, were first used in combat shortly after the war began. Alternating between restricted and unrestricted submarine warfare during the First Battle of the Atlantic, they were employed by the Kaiserliche Marine in a strategy of weakening the British Empire by attacking its merchant shipping. In 1915, the RMS Lusitania liner was sunk with United States citizens aboard, affecting the United States' entry into the war.

Aftermath

Main article: Aftermath of World War I

The First World War ended with a Europe scarred by trenches, spent of resources, and littered with the bodies of the millions who died in battle. The direct consequences of WWI brought many old regimes crashing to the ground, and ultimately, would lead to the end of 300 years of European hegemony.

The spread of war

1914

• July 27: Austria-Hungary declares war on Serbia.
• August 1: Germany declares war on Russia.
• August 2: German troops occupy Luxembourg