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World War I
Clockwise from top: Trenches on the Western Front; a British Mark IV tank crossing a trench; Royal Navy battleship HMS Irresistible sinking after striking a mine at the Battle of the Dardanelles; a Vickers machine gun crew with gas masks, and German Albatros D.III biplanes
Date July 28 1914 – November 11 1918 Location Europe, Africa and the Middle East (briefly in China and the Pacific Islands) Result Allied victory; end of the German, Russian, Ottoman, and Austro-Hungarian Empires; foundation of new countries in Europe and the Middle East; transfer of German colonies to other powers; establishment of the League of Nations.
Belligerents
Allied (Entente) Powers	Central Powers
Commanders
Leaders and commanders	Leaders and commanders
Casualties and losses
Military dead: 5,525,000 Military wounded: 12,831,500 Military missing: 4,121,000Evans, David. Teach yourself, the First World War, Hodder Arnold, 2004.p.188 ...further details.	Military dead: 4,386,000 Military wounded: 8,388,000 Military missing: 3,629,000 ...further details.

World War I, also known as the First World War, the Great War and the War To End All Wars, was a global military conflict which took place primarily in Europe from 1914 to 1918.The First World War. Over 40 million casualties resulted, including approximately 20 million military and civilian deaths.Military Casualties of World War One. Over 60 million European soldiers were mobilized from 1914 to 1918.The Treaty of Versailles and its Consequences The immediate cause of the war was the June 28, 1914 assassination of Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, by Gavrilo Princip, a Bosnian Serb citizen of Austria-Hungary and member of the Black Hand. The retaliation by Austria-Hungary against Serbia activated a series of alliances that set off a chain reaction of war declarations. Within a month, much of Europe was in a state of open warfare.

The war was propagated by two major alliances. The Entente Powers initially consisted of France, the United Kingdom, Russia and their associated empires and dependencies. Numerous other states joined these allies, most notably Italy in April 1915, and the United States in April 1917. The Central Powers, so named because of their central location on the European continent, initially consisted of Germany and Austria-Hungary and their associated empires. The Ottoman Empire joined the Central Powers in October 1914, followed a year later by Bulgaria. By the conclusion of the war, only The Netherlands, Switzerland, Spain and the Scandinavian nations remained officially neutral among the European countries, though many of those provided financial and material support to one side or the other.

The fighting of the war mostly took place along several fronts that broadly encircled the European continent. The Western Front was marked by a system of trenches, breastworks, and fortifications separated by an area known as no man\'s land.Ashworth, Tony. Trench warfare 1914–1918, pp3–4. 2000: Macmillan Press, London. These fortifications stretched 475 miles (more than 600 kilometres) and precipitated a style of fighting known as trench warfare. On the Eastern Front, the vast eastern plains and limited rail network prevented a trench warfare stalemate, though the scale of the conflict was just as large as on the Western Front. The Middle Eastern Front and the Italian Front also saw heavy fighting, while hostilities also occurred at sea, and for the first time, in the air.

The war was ended by several treaties, most notably the Treaty of Versailles, signed on June 28, 1919, though the Allied powers had an armistice with Germany in place since November 11, 1918. One of the most striking results of the war was a large redrawing of the map of Europe. All of the Central Powers lost territory, and many new nations were created. The German Empire lost its colonial possessions and was saddled with accepting blame for the war, as well as paying punitive reparations for it. The Austro-Hungarian and Ottoman empires were completely dissolved. Austria-Hungary was carved up into several successor states including Austria, Hungary, Czechoslovakia, and Yugoslavia. The Ottoman Empire disintegrated, and much of its non-Anatolian territory was awarded as protectorates of various Allied powers, while the remaining Turkish core was reorganized as the Republic of Turkey. The Russian Empire, which had withdrawn from the war in 1917, lost much of its western frontier as the newly independent nations of Estonia, Finland, Latvia, Lithuania, and Poland were carved from it. After the war, the League of Nations was created as an international organization designed to avoid future wars by giving nations a means of solving their differences diplomatically. World War I marked the end of the world order which had existed after the Napoleonic Wars, and was an important factor in the outbreak of World War II.

Causes

Main article: Causes of World War I

A graphic depiction of the state of international relations in pre-WWI Europe. Italy joined the Triple Entente in April 1915.

On 28 June 1914, Gavrilo Princip, a Bosnian Serb student, shot and killed Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, in Sarajevo. Princip was a member of Young Bosnia, a group whose aims included the unification of the South Slavs and independence from Austria-Hungary. The assassination in Sarajevo set into motion a series of fast-moving events that eventually escalated into full-scale war.First World War.com Primary Documents: Archduke Franz Ferdinand\'s Assassination, 28 June 1914 (2002-11-03). Retrieved on 2008-02-17. Austria-Hungary demanded action by Serbia to punish those responsible and, when Austria-Hungary deemed Serbia had not complied, declared war. Major European powers were at war within weeks because of overlapping agreements for collective defense and the complex nature of international alliances.

See also: Black Hand

Arms race

See also: Dreadnought

The naval race between Britain and Germany was intensified by the 1906 launch of HMS Dreadnought —a revolutionary craft whose size and power rendered previous battleships obsolete. Britain also maintained a large naval lead in other areas particularly over Germany and Italy. Paul Kennedy pointed out both nations believed Alfred Thayer Mahan\'s thesis of command of the sea as vital to great nation status; experience with guerre de course would prove Mahan wrong.

David Stevenson described the arms race as "a self-reinforcing cycle of heightened military preparedness."Stevenson, D., Armaments and the Coming of War: Europe, 1904-1914, 1996 (Oxford University Press) David Herrmann viewed the shipbuilding rivalry as part of a general movement in the direction of war.Herrmann, David G. The Arming of Europe and the Making of the First World War(1996) The revisionist Niall Ferguson, however, argued Britain\'s ability to maintain an overall lead signified this was not a factor in the oncoming conflict. Ferguson, Niall (1999). The Pity of War. Basic Books, 563. ISBN 046505711X. 

The cost of the arms race was felt in both Britain and Germany. The total arms spending by the six Great Powers (Britain, Germany, France, Russia, Austria-Hungary and Italy) increased by 50% between 1908 and 1913. Fromkin, David (2004). "Chapter 15: Europe Goes to the Brink", Europe\'s Last Summer: Who Started the Great War in 1914?. New York: Alfred A. Knopf, 94. ISBN 0-375-72575-X. 

Plans, distrust, and mobilization

Closely related is the thesis adopted by many political scientists that the mobilization plans of Germany, France and Russia automatically escalated the conflict. Fritz Fischer emphasized the inherently aggressive nature of the Schlieffen Plan, which outlined a two-front strategy. Fighting on two fronts meant Germany had to eliminate one opponent quickly before taking on the other. It called for a strong right flank attack, to seize Belgium and cripple the French army by pre-empting its mobilization. After the attack, the German army would rush east by railroad and quickly destroy the slowly mobilizing Russian forces.Fischer, Fritz. Griff nach der Weltmacht: Die Kriegzielpolitik des kaiserlichen Deutschland 1914-1918 (published in English as Germany\'s Aims in the First World War)

France\'s Plan XVII envisioned a quick thrust into the Ruhr Valley, Germany’s industrial heartland, which would in theory cripple Germany\'s ability to wage a modern war.

Russia\'s Plan XIX foresaw a mobilization of its armies against both Austria-Hungary and Germany.

All three plans created an atmosphere in which speed was one of the determining factors for victory. Elaborate timetables were prepared; once mobilization had begun, there was little possibility of turning back. Diplomatic delays and poor communications exacerbated the problems.

Also, the plans of France, Germany and Russia were all biased toward the offensive, in clear conflict with the improvements of defensive firepower and entrenchment.Snyder, Jack. Ideology of the Offensive. Ithaca: Cornell University Press, 1984; Dupuy, Trevor N., Colonel, USA (rtd). Numbers Predictions, and War. Philadelphia: Bobbs-Merrill, 1979.First World War.com A map of the French and German war plans.First World War.com French and German war plans.

Militarism and autocracy

President Woodrow Wilson of the United States and others blamed the war on militarism. 30 October 1918 in Herbert Hoover, Ordeal of Woodrow Wilson p. 47 Some argued that aristocrats and military Ă©lites had too much power in countries such as Germany, Russia, and Austria-Hungary. War was thus a consequence of their desire for military power and disdain for democracy. This theme figured prominently in anti-German propaganda. Consequently, supporters of this theory called for the abdication of rulers such as Kaiser Wilhelm II, as well as an end to aristocracy and militarism in general. This platform provided some justification for the American entry into the war when the Russian Empire surrendered in 1917.

The Allies consisted of Great Britain and France, both democracies, fighting the Central Powers, which included Germany, Austro-Hungary, and the Ottoman Empire. Russia, one of the Allied Powers, was an empire until 1917, but it was opposed to the subjugation of Slavic peoples by Austro-Hungary. Against this backdrop, the view of the war as one of democracy versus dictatorship initially had some validity, but lost credibility as the conflict dragged on.

Wilson hoped the League of Nations and disarmament would secure a lasting peace. He also acknowledged that variations of militarism, in his opinion, existed within the British and French Empires.

Balance of power

Political cartoon depicting the tangled web of European alliances.

One of the goals of the foreign policies of the Great Powers in the pre-war years was to maintain the \'Balance of Power\' in Europe. This evolved into an elaborate network of secret and public alliances and agreements. For example, after the Franco-Prussian War (1870–71), Britain seemed to favor a strong Germany, as it helped to balance its traditional enemy, France. After Germany began its naval construction plans to rival that of Britain, this stance shifted. France, looking for an ally to balance the threat created by Germany, found it in Russia. Austria-Hungary, facing a threat from Russia, sought support from Germany.

When World War I broke out, these treaties only partially determined who entered the war on which side. Britain had no treaties with France or Russia, but entered the war on their side. Italy had a treaty with both Austria-Hungary and Germany, yet did not enter the war with them; Italy later sided with the Allies. Perhaps the most significant treaty of all was the initially defensive pact between Germany and Austria-Hungary, which Germany in 1909 extended by declaring that Germany was bound to stand with Austria-Hungary even if it had started the war.Fromkin, David (2004). "Chapter 45: What Did Not Happen", Europe\'s Last Summer: Who Started the Great War in 1914?. New York: Alfred A. Knopf, 266–267. ISBN 0-375-72575-X. 

Economic imperialism

Vladimir Lenin asserted that imperialism was responsible for the war. He drew upon the economic theories of Karl Marx and English economist John A. Hobson, who predicted that unlimited competition for expanding markets would lead to a global conflict.“Imperialism" (1902) fordham.edu website This argument was popular in the wake of the war and assisted in the rise of Communism. Lenin argued that the banking interests of various capitalist-imperialist powers orchestrated the war.1917 pamphlet "Imperialism: The Highest Stage of Capitalism".

Trade barriers

Cordell Hull, American Secretary of State under Franklin Roosevelt, believed that trade barriers were the root cause of both World War I and World War II. In 1944, he helped design the Bretton Woods Agreements to reduce trade barriers and eliminate what he saw as the cause of the conflicts.Hull, Cordell (1948). The Memoirs of Cordell Hull: vol. 1. New York: Macmillan, 81. 

Ethnic and political rivalries

A Balkan war between Austria-Hungary and Serbia was considered inevitable, as Austria-Hungary’s influence waned and the Pan-Slavic movement grew. The rise of ethnic nationalism coincided with the growth of Serbia, where anti-Austrian sentiment was perhaps most fervent. Austria-Hungary had occupied the former Ottoman province of Bosnia-Herzegovina, which had a large Serb population, in 1878. It was formally annexed by Austria-Hungary in 1908. Increasing nationalist sentiment also coincided with the decline of the Ottoman Empire. Russia supported the Pan-Slavic movement, motivated by ethnic and religious loyalties and a rivalry with Austria dating back to the Crimean War. Recent events such as the failed Russian-Austrian treaty and a century-old dream of a warm water port also motivated St. Petersburg.Web reference (PDF).

Myriad other geopolitical motivations existed elsewhere as well, for example France\'s loss of Alsace and Lorraine in the Franco-Prussian War helped create a sentiment of irredentist revanchism in that country. France eventually allied itself with Russia, creating the likelihood of a two-front war for Germany.

See also: Powder keg of Europe

July crisis and declarations of war

Declaration of war from the German Empire in 1914

The Austro-Hungarian government used the assassination of Archduke Franz Ferdinand as a pretext to deal with the Serbian question, supported by Germany. On 23 July 1914, an ultimatum was sent to Serbia with demands so extreme that it was rejected. The Serbians, relying on support from Russia, instead ordered mobilization. In response to this, Austria-Hungary issued a declaration of war on 28 July. Initially, Russia ordered partial mobilization, directed at the Austrian frontier. On 31 July, after the Russian General Staff informed the Czar that partial mobilization was logistically impossible, a full mobilization was ordered. The Schlieffen Plan, which relied on a quick strike against France, could not afford to allow the Russians to mobilize without launching an attack. Thus, the Germans declared war against Russia on 1 August and on France two days later. Germany then violated Belgium\'s neutrality by the German advance through it to Paris, and this brought the British Empire into the war. With this, five of the six European powers were now involved in the largest continental European conflict since the Napoleonic Wars.Joll, James. The Origins of the First World War, 2nd ed. (Harlow, 1992), pp. 10–38

Chronology

European military alliances in 1914; Central Powers purplish-red, Entente Powers pale green, and neutral countries yellow

Opening hostilities

Confusion among the Central Powers

The strategy of the Central Powers suffered from miscommunication. Germany had promised to support Austria-Hungary’s invasion of Serbia, but interpretations of what this meant differed. Austro-Hungarian leaders believed Germany would cover its northern flank against Russia. Germany, however, envisioned Austria-Hungary directing the majority of its troops against Russia, while Germany dealt with France. This confusion forced the Austro-Hungarian Army to divide its forces between the Russian and Serbian fronts.

African campaigns

Main article: African theatre of World War I

Some of the first clashes of the war involved British, French and German colonial forces in Africa. On 7 August, French and British troops invaded the German protectorate of Togoland. On 10 August German forces in South-West Africa attacked South Africa; sporadic and fierce fighting continued for the remainder of the war.

Haut-Rhin, France, 1917

Serbian campaign

Main article: Serbian Campaign (World War I)

The Serbian army fought the Battle of Cer against the invading Austrians, beginning on 12 August, occupying defensive positions on the south side of the Drina and Sava rivers. Over the next two weeks Austrian attacks were thrown back with heavy losses, which marked the first major Allied victory of the war and dashed Austrian hopes of a swift victory. As a result, Austria had to keep sizable forces on the Serbian front, weakening their efforts against Russia. Serbian troops then defeated Austro-Hungarian forces at the Battle of Kolubara, leading to 240,000 Austro-Hungarian casualties. The Serbian Army lost 170,000 troops.

German forces in Belgium and France

Main article: Western Front (World War I)

The remains of German soldiers at Verdun. The Battle of Verdun resulted in more than a quarter of a million deaths and approximately half a million wounded.

Initially, the Germans had great success in the Battle of the Frontiers (14 August–24 August). Russia, however, attacked in East Prussia and diverted German forces intended for the Western Front. Germany defeated Russia in a series of battles collectively known as the First Battle of Tannenberg (17 August – 2 September), but this diversion exacerbated problems of insufficient speed of advance from rail-heads not foreseen by the German General Staff. Originally, the Schlieffen Plan called for the right flank of the German advance to pass to the west of Paris. However, the capacity and low speed of horse-drawn transport hampered the German supply train, allowing French and British forces to finally halt the German advance east of Paris at the First Battle of the Marne (5 September–12 September). The Central Powers were thereby denied a quick victory and forced to fight a war on two fronts. The German army had fought its way into a good defensive position inside France and had permanently incapacitated 230,000 more French and British troops than it had lost itself. Despite this, communications problems and questionable command decisions cost Germany the chance for an early victory.

Asia and the Pacific

Main article: Asian and Pacific theatre of World War I

New Zealand occupied German Samoa (later Western Samoa) on 30 August. On 11 September the Australian Naval and Military Expeditionary Force landed on the island of Neu Pommern (later New Britain), which formed part of German New Guinea. Japan seized Germany’s Micronesian colonies and after the Battle of Tsingtao, the German coaling port of Qingdao, in the Chinese Shandong peninsula. Within a few months, the Allied forces had seized all the German territories in the Pacific.

In the trenches: Infantry with gas masks, Ypres, 1917

Early stages

Trench warfare begins

This section is missing citations or needs footnotes. Using inline citations helps guard against copyright violations and factual inaccuracies. (February 2008)

Main article: Western Front (World War I)

Military tactics before World War I had failed to keep pace with advances in technology. It demanded the building of impressive defence systems, which out-of-date tactics could not break through for most of the war. Barbed wire was a significant hindrance to massed infantry advances. Artillery, vastly more lethal than in the 1870s, coupled with machine guns, made crossing open ground very difficult. The Germans introduced poison gas; it soon became used by both sides, though it never proved decisive in winning a battle. Its effects were brutal, however, causing slow and painful death, and poison gas became one of the most-feared and best-remembered horrors of the war. Commanders on both sides failed to develop tactics for breaking through entrenched positions without heavy casualties. In time, however, technology began also to yield new offensive weapons, such as the tank. Britain and France were its primary users; the Germans employed captured Allied tanks and small numbers of their own design.

After the First Battle of the Marne, both Entente and German forces began a series of outflanking maneuvers, in the so-called \'Race to the Sea\'. Britain and France soon found themselves facing entrenched German forces from Lorraine to Belgium\'s Flemish coast. Britain and France sought to take the offensive, while Germany defended the occupied territories; consequentially, German trenches were generally much better constructed than those of their enemy. Anglo-French trenches were only intended to be \'temporary\' before their forces broke through German defenses. Both sides attempted to break the stalemate using scientific and technological advances. In April 1915, the Germans used chlorine gas for the first time (in violation of the Hague Convention), opening a 6 kilometres (4 mi) hole in the Allied lines when British and French colonial troops retreated. Canadian soldiers closed the breach at the Second Battle of Ypres. At the Third Battle of Ypres, Canadian and ANZAC troops took the village of Passchendaele.

On 1 July 1916, the first day of the Battle of the Somme, the British Army endured the bloodiest day in its history, suffering 57,470 casualties and 19,240 dead. Most of the casualties occurred in the first hour of the attack. The entire offensive cost the British Army almost half a million men.Duffy, Michael. First World War.com (English). Retrieved on February 25, 2007.

A French assault on German positions. Champagne, France, 1917.

Neither side proved able to deliver a decisive blow for the next two years, though protracted German action at Verdun throughout 1916, combined with the Entente\'s failure at the Somme,^{[citation needed]} brought the exhausted French army to the brink of collapse. Futile attempts at frontal assault, a rigid adherence to an ineffectual method,^{[citation needed]} came at a high price for both the British and the French poilu (infantry) and led to widespread mutinies, especially during the Nivelle Offensive.

Canadian troops advancing behind a British Mark II tank at the Battle of Vimy Ridge.

Throughout 1915–17, the British Empire and France suffered more casualties than Germany, due both to the strategic and tactical stances chosen by the sides. At the strategic level, while the Germans only mounted a single main offensive at Verdun, the Allies made several attempts to break through German lines. At the tactical level, the German defensive doctrine was well suited for trench warfare, with a relatively lightly defended "sacrificial" forward position,^{[citation needed]} and a more powerful main position from which an immediate and powerful counter-offensive could be launched. This combination usually was effective in pushing out attackers at a relatively low cost to the Germans.^{[citation needed]} In absolute terms, of course, the cost in lives of men for both attack and defense was astounding.

Ludendorff wrote on the fighting in 1917. "The 25th of August concluded the second phase of the Flanders battle. It had cost us heavily…. The costly August battles in Flanders and at Verdun imposed a heavy strain on the Western troops. In spite of all the concrete protection they seemed more or less powerless under the enormous weight of the enemy’s artillery. At some points they no longer displayed the firmness which I, in common with the local commanders, had hoped for. The enemy managed to adapt himself to our method of employing counter attacks… I myself was being put to a terrible strain. The state of affairs in the West appeared to prevent the execution of our plans elsewhere. Our wastage had been so high as to cause grave misgivings, and had exceeded all expectation."

On the battle of the Menin Road Ridge he wrote "Another terrific assault was made on our lines on the 20th September…. The enemy’s onslaught on the 20th was successful, which proved the superiority of the attack over the defence. Its strength did not consist in the tanks; we found them inconvenient, but put them out of action all the same. The power of the attack lay in the artillery, and in the fact that ours did not do enough damage to the hostile infantry as they were assembling, and above all, at the actual time of the assault."John Terraine "Ordeal of Victory"

Officers and senior enlisted men of the Bermuda Militia Artillery\'s Bermuda Contingent, Royal Garrison Artillery, in Europe.

Around 800,000 soldiers from the British Empire were on the Western Front at any one time.^{[citation needed]} 1,000 battalions, occupying sectors of the line from the North Sea to the Orne River, operated on a month-long four-stage rotation system, unless an offensive was underway. The front contained over 9,600 kilometres (5,965 mi) of trenches. Each battalion held its sector for about a week before moving back to support lines and then further back to the reserve lines before a week out-of-line, often in the Poperinge or Amiens areas.

In the 1917 Battle of Arras the only significant British military success was the capture of Vimy Ridge by the Canadian Corps under Sir Arthur Currie and Julian Byng. The assaulting troops were able for the first time to overrun, rapidly reinforce and hold the ridge defending the coal-rich Douai plain."Vimy Ridge, Canadian National Memorial" (2007) Australians on the Western Front 1914-1918 New South Wales Department of Veteran\'s Affairs and Board of Studies

Naval war

Main article: Naval Warfare of World War I

A battleship squadron of the Hochseeflotte at sea.

At the start of the war, the German Empire had cruisers scattered across the globe, some of which were subsequently used to attack Allied merchant shipping. The British Royal Navy systematically hunted them down, though not without some embarrassment from its inability to protect allied shipping. For example, the German detached light cruiser Emden, part of the East-Asia squadron stationed at Tsingtao, seized or destroyed 15 merchantmen, as well as sinking a Russian cruiser and a French destroyer. However, the bulk of the German East-Asia squadron—consisting of the armoured cruisers Scharnhorst and Gneisenau, light cruisers Nürnberg and Leipzig and two transport ships—did not have orders to raid shipping and was instead underway to Germany when it encountered elements of the British fleet. The German flotilla, along with Dresden, sank two armoured cruisers at the Battle of Coronel, but was almost completely destroyed at the Battle of the Falkland Islands in December 1914, with only Dresden escaping.John M. Taylor, "Audacious Cruise of the Emden", The Quarterly Journal of Military History, Volume 19, Number 4, Summer 2007, pp. 39–47

Soon after the outbreak of hostilities, Britain initiated a naval blockade of Germany. The strategy proved effective, cutting off vital military and civilian supplies, although this blockade violated generally accepted international law codified by several international agreements of the past two centuries.Keene, Jennifer D.. World War I (The Greenwood Press Daily Life Through History Series). Westport, Conn: Greenwood Press, 5. ISBN 0-313-33181-2.  Britain mined international waters to prevent any ships from entering entire sections of ocean, causing danger to even neutral ships. A Naval History of World War 1. New York: Routledge, 293. ISBN 1-85728-498-4.  Since there was limited response to this tactic, Germany expected a similar response to its unrestricted submarine warfare.Zieger, Robert H. (2001). America\'s Great War: World War I and the American experience. Lanham, Md: Rowman & Littlefield Publishers, 50. ISBN 0-8476-9645-6. 

HMS Lion burning during the Battle of Jutland, after having been hit by a salvo from SMS LĂĽtzow.

The 1916 Battle of Jutland (German: Skagerrakschlacht, or "Battle of the Skagerrak") developed into the largest naval battle of the war, the only full-scale clash of battleships during the war. It took place on 31 May–1 June, 1916, in the North Sea off Jutland. The Kaiserliche Marine\'s High Seas Fleet, commanded by Vice Admiral Reinhard Scheer, squared off against the Royal Navy\'s Grand Fleet, led by Admiral Sir John Jellicoe. The engagement was a standoff, as the Germans, outmaneuvered by the larger British fleet, managed to escape and inflicted more damage to the British fleet than they received. Strategically, however, the British asserted their control of the sea, and the bulk of the German surface fleet remained confined to port for the duration of the war.

German U-boats attempted to cut the supply lines between North America and Britain.Coast Guard in the North Atlantic War. Retrieved on 2007-10-30. The nature of submarine warfare meant that attacks often came without warning, giving the crews of the merchant ships little hope of survival.Gilbert, Martin. The First World War: A Complete History. Clearwater, Fla: Owl Books, 306. ISBN 0-8050-7617-4.  The United States launched a protest, and Germany modified its rules of engagement. After the infamous sinking of the passenger ship RMS Lusitania in 1915, Germany promised not to target passenger liners, while Britain armed its merchant ships. Finally, in early 1917 Germany adopted a policy of unrestricted submarine warfare, realizing the Americans would eventually enter the war.Jones, Howard (2001). Crucible of power: a history of U. S. foreign relations since 1897. Wilmington, Del: SR Books, 80. ISBN 0-8420-2918-4.  Germany sought to strangle Allied sea lanes before the U.S. could transport a large army overseas.

The U-boat threat lessened in 1917, when merchant ships entered convoys escorted by destroyers. This tactic made it difficult for U-boats to find targets, which significantly lessened losses; after the introduction of hydrophone and depth charges, accompanying destroyers might actually attack a submerged submarine with some hope of success. The convoy system slowed the flow of supplies, since ships had to wait as convoys were assembled. The solution to the delays was a massive program to build new freighters. Troop ships were too fast for the submarines and did not travel the North Atlantic in convoys.Nova Scotia House of Assembly Committee on Veterans\' Affairs. Retrieved on 2007-10-30.Greek American Operational Group OSS, Part 3 continued. Retrieved on 2007-10-30.

The First World War also saw the first use of aircraft carriers in combat, with HMS Furious launching Sopwith Camels in a successful raid against the Zeppelin hangars at Tondern in July 1918, as well as blimps for antisubmarine patrol.Price, Alfred. Aircraft versus the Submarine. (London: Wiliam Kimber, 1973).

Southern theatres

Ottoman Empire

Main article: Middle Eastern theatre of World War I

The Ottoman Empire joined the Central Powers in the war, the secret Ottoman-German Alliance having been signed in August 1914. It threatened Russia\'s Caucasian territories and Britain\'s communications with India via the Suez Canal. The British and French opened overseas fronts with the Gallipoli (1915) and Mesopotamian campaigns. In Gallipoli, the Turks successfully repelled the British, French and Australian and New Zealand Army Corps (ANZACs). In Mesopotamia, by contrast, after the disastrous Siege of Kut (1915–16), British Imperial forces reorganised and captured Baghdad in March 1917. Further to the west, in the Sinai and Palestine Campaign, initial British setbacks were overcome when Jerusalem was captured in December 1917. The Egyptian Expeditionary Force, under Field Marshal Edmund Allenby, broke the Ottoman forces at the Battle of Megiddo in September 1918.

Russian armies generally had the best of it in the Caucasus. Vice-Generalissimo Enver Pasha, supreme commander of the Turkish armed forces, was ambitious and dreamed of conquering central Asia. He was, however, a poor commander.Fromkin, David (2001). A peace to end all peace: the fall of the Ottoman Empire and the creation of the modern Middle East. New York: H. Holt, 119. ISBN 0-8050-6884-8.  He launched an offensive against the Russians in the Caucasus in December 1914 with 100,000 troops; insisting on a frontal attack against mountainous Russian positions in winter, he lost 86% of his force at the Battle of Sarikamis.Hinterhoff, Eugene (1984). The Campaign in Armenia. Marshall Cavendish Illustrated Encyclopedia of World War I, vol ii. New York: Marshall Cavendish Corporation, pp.499-503. ISBN 0-86307-181-3. 

The Russian commander from 1915 to 1916, General Yudenich, drove the Turks out of most of the southern Caucasus with a string of victories.Hinterhoff, Eugene (1984). The Campaign in Armenia. Marshall Cavendish Illustrated Encyclopedia of World War I, vol ii. New York: Marshall Cavendish Corporation, pp.499-503. ISBN 0-86307-181-3.  In 1917, Russian Grand Duke Nicholas assumed command of the Caucasus front. Nicholas planned a railway from Russian Georgia to the conquered territories, so that fresh supplies could be brought up for a new offensive in 1917. However, in March 1917, (February in the pre-revolutionary Russian calendar), the Czar was overthrown in the February Revolution and the Russian Caucasus Army began to fall apart. In this situation, the army corps of Armenian volunteer units realigned themselves under the command of General Tovmas Nazarbekian, with Dro as a civilian commissioner of the Administration for Western Armenia. The front line had three main divisions: Movses Silikyan, Andranik, and Mikhail Areshian. Another regular unit was under Colonel Korganian. There were Armenian partisan guerrilla detachments (more than 40,000Boghos Nubar the president of the "Armenian National Assembly" declared to Paris Peace Conference, 1919 through a letter to French Foreign Office - December 3, 1918) accompanying these main units.

The Arab Revolt was a major cause of the Ottoman Empire\'s defeat. The revolts started with the Battle of Mecca by Sherif Hussain of Mecca with the help of Britain in June 1916, and ended with the Ottoman surrender of Damascus. Fakhri Pasha the Ottoman commander of Medina showed stubborn resistance for over two and half years during the Siege of Medina.

Along the border of Italian Libya and British Egypt, the Senussi tribe, incited and armed by the Turks, waged a small-scale guerrilla war against Allied troops. According to Martin Gilbert\'s The First World War, the British were forced to dispatch 12,000 troops to deal with the Senussi. Their rebellion was finally crushed in mid-1916.

Italian participation

Main article: Italian Campaign (World War I)

Italy had been allied with the German and Austro-Hungarian Empires since 1882 as part of the Triple Alliance. However, the nation had its own designs on Austrian territory in Trentino, Istria and Dalmatia. Rome had a secret 1902 pact with France, effectively nullifying its alliance.Triple Alliance. At the start of hostilities, Italy refused to commit