Imperial, territorial, and economic rivalries led to the “Great War” between the Central Powers and the Allies. About 10 million combatants killed, 20 million wounded. These are key dates in the war.
Austria-Hungary declares war on Serbia (July 28).
Germany declares war on Russia (Aug. 1).
Germany declares war on France (Aug. 3)
Germany invades Belgium (Aug. 4).
Britain declares war on Germany (Aug. 4).
Austria-Hungary declares war on Russia and Serbia declares war on Germany (Aug. 6).
Germans defeat Russians in Battle of Tannenberg on Eastern Front (Aug.).
First Battle of the Marne begins and German drive is stopped 25 miles from Paris (Sept. 6–9).
First Battle of Ypres begins (Oct. 18).
Turkey enters the war allied with Germany (Oct. 29). By end of year, war on the Western Front is “positional” in the trenches
German submarine blockade of Great Britain begins (Feb.).
The Dardanelles Campaign begins (Feb. 19).
The Second Battle of Ypres begins (April 22). Germans use poison gas for the first time during this battle.
The Gallipoli Campaign begins (April 25).
The Lusitania sunk by German submarine—1,198 lost, including 128 Americans (May 7).
Italy declares enters the war on the side of the Allies (May 23).
On Eastern Front, German and Austrian “great offensive” conquers all of Poland and Lithuania; Russians lose 1 million men (by Sept. 6).
“Great Fall Offensive” by Allies results in little change from 1914 (Sept.–Oct.).
Britain and France declare war on Bulgaria (Oct. 14). The Allies begin withdrawing troops from Gallipoli (Dec. 19).
Battle of Verdun begins (Feb. 21). Germans and French each lose about 350,000 men in the longest battle of the war.
Extended submarine warfare begins (March).
The British-German sea Battle of Jutland begins (May 31). The British lose more ships, but German fleet never ventures forth again.
On the Eastern Front, the Brusilov offensive begins (June 4). The battle cost the Austrians 1.5 million men and the Russians lost 1 million troops.
Battle of the Somme begins (July 1). The British lose over 400,000; French, 200,000; Germans, about 450,000; all with no strategic results. Tanks are first used in battle in this campaign.
Romania declares war on Austria-Hungary (Aug. 27).
Bucharest captured (Dec. 9).
Germany resumes the use of unrestricted submarine warfare (Feb. 1).
Germany's foreign secretary, Arthur Zimmermann, sends a coded telegram to Mexico, asking it to join the Central Powers if the U.S. enters the war (Jan. 19). Britain intercepts and decodes the message.
Tsar Nicholas II of Russia abdicates (March 15).
The U.S. declares war on Germany (April 6).
The Third Battle of Ypres (also known as Passchendaele) begins (July 31).
In the Battle of Caporetto, the Germano-Austrian military forces the Italians to retreat. They lose 600,000 prisoners and deserters (Oct. 24–Dec.20).
The Bolsheviks overthrow the Russian government in the Russian Revolution (Nov. 7). The Bolsheviks want out of the war.
In the Battle of Cambrai, Britain launches its first large tank attack (Nov.20–Dec. 3).
U.S. declares war on Austria-Hungary (Dec. 7).
The British capture Jerusalem from the Turks (Dec. 8).
Armistice is signed between new Russian Bolshevik government and Germans (Dec. 15).
Russia and the Central Powers sign the Treaty of Brest-Litovsk (March 3).
Germany begins the Great offensive (March 21). It continues through June.
Baron Manfred von Richthofen, the notorious World War I German flying ace known as the "Red Baron," was killed in action (April 21).
Americans' first important battle role at Château-Thierry—as they and French stop German advance (June).
Second Battle of the Marne begins (July 15). The last great German offensive is successfully thwarted by the Allies.
Repulsed by the Allies, Germany retreats to the Hindenburg line (July 22).
The Allies successfully advance to the Hindenburg line (Aug. 8).
British offensive in Palestine results in the fall of Turks at Megiddo (Sep. 19).
Germans ask for armistice (Oct. 4).
British armistice with Turkey (Oct. 30).
German Kaiser abdicates (Nov. 9).
Italy wins a decisive victory over Austria-Hungary at Vittorio Veneto in northeast Italy (Oct.). Austria-Hungary surrenders. The Armistice of Villa Giusti is signed, ending the war on the Italian Front (Nov. 3).
Hostilities cease on the Western Front and the Armistice of Compiègne is signed, ending World War I (Nov. 11).
The Treaty of Versailles is signed, officially ending the war (June 28)..