Important Dates in World War I: A Timeline

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This World War I Timeline is a brief overview of the main points that defined the war; with some of the major battles included. The two sides of World War I were the Central Powers and the Allied Powers, which were also known as the Triple Entente. The Central Powers were made up of Germany, Hungary, Turkey, and Bulgaria. The Allied Powers were primarily comprised of Belgium, Serbia, France, Russia, British Empire, Italy, Romania, and the United States.


June 28 – Gavrilo Princip, a Serbian nationalist, assassinated Austrian Archduke Francis Ferdinand in Sarajevo

July 28 – Austria declared war on Serbia.

August 1-4 – World War I begins when Germany declared war on Russia and France; Great Britain declares war on Germany.

August 13 – Because of their alliance with Great Britain, Japan declares war on Germany.

August 19 – President Woodrow Wilson declares United States neutrality.

First Battle of the Marne

September 5-12, 1914 – The First Battle of the Marne was one of the most important battles of World War I because it ended Allied hopes of a quick ending for the war. About one hundred thousand soldiers were killed or injured.

October 29 – Turkey entered the war on the side of the Germans.

November 2 – Russia declared war on Turkey.

November 5 – France and Great Britain declared war on Turkey.

December – The first zeppelins are spotted over the English coast.


April 22 – Poison gas is used for the first time by the Germans at Ypres.

Second Battle of Ypres

Starting April 22 and lasting until May 25, 1915 - At the Second Battle of Ypres the German military used the first large scale poison gas attack in the history of warfare. They launched chlorine gas against French troops and the devastating effects shocked both sides preventing the Germans from fully taking advantage of the results. Although the battle itself did not result in significant gains for either side, the introduction of poison gas changed warfare forever.

May 7 – The Lusitania was sunk by a German U-Boat. This outraged many Americans because of the American passengers that had been aboard the boat.

May 23 – Italy joined the Allies in the war.

Gallipoli Campaign

March 1915 – January 1916 The Gallipoli Campaign was the unsuccessful Allied attempt to invade Turkey. Although technically a failure the campaign did allow the British to later gain control of Palestine and prevented the Germans from beginning a planned offensive in France.


Battle of Verdun

February 21 - Dec 18, 1916 – The Battle of Verdun was the longest military engagement of World War I, lasting almost ten months and resulting in nearly one million casualties.

April – Romania joined the Allies in the war.

November 28 – The first German air raid over London.

December – David Lloyd George became Prime Minister of the United Kingdom.


February 1 – Initiation of the unrestricted use of German U-boats to sink all neutral or allied ships. Within one month millions of tons of shipping materials and their goods were sunk making neutral countries reluctant to ship goods to allied countries without a military convoy.

April 6 – America declares war on Germany in response to the sinking of American ships by German U-boats.

Battle of Jutland

May 31-June 1, 1916 – The Battle of Jutland was originally claimed as a victory for the German naval forces, however, the battle ultimately left the German fleet with few sea worthy vessels and their strategy began to rely almost exclusively on their submarines. The Germans would not again try to breach the lines of the British fleet again during World War I.

June – The first American troops arrive in France.

December – Treaty of Brest-Litovsk establishes peace between Russia and Germany. Russians must surrender the Ukraine, Poland, and other areas as well as cease all Socialist propaganda and pay to have their prisoners returned.


Battle of Passchendaele

July-Nov, 1917 - The Battle of Passchendaele, sometimes known as the Third Battle of Ypres, is one of the best, and most horrific, examples of trench warfare. Over 300,000 Allied and 250,000 Central Power soldiers died in this four month battle with little gained on either side although the British and Canadian forces leading the offensive were able to claim a technical victory.

Battle of Caporetto

October 24-November 19, 1917- During the Battle of Caporetto the combined forces of the German and Hungarian armies achieved one of the greatest victories of World War I, devastating the Italian army. After bombarding the Italians with artillery the German and Austrian troops were able to push into Italian territory nearly 15 miles in a single day using flamethrowers and grenades. The battle led to the resignation of Italian Commander in Chief Luigi Cardona and the shift from an offensive strategy on the part of the Italians to a defensive strategy.


January 8 – Fourteen Point Peace Plan proposed by President Wilson. This plan includes the creation of the League of Nations.

The 2nd Battle of the Somme

March 1918 – The Battle of the Somme was the first major battle for United States forces in World War I. It was also the first large offensive move on the part of Germany in more than a year. Ultimately the Germans gained 40 miles at the cost of hundreds of thousands of causalities.

April – The Royal Air Force is formed by combining the Royal Flying Corps and the Royal Naval Air Service.

June – Germans defeated by Americans at Belleau Wood

Battle of Amiens

August 1918 - During the Battle of Amiens the Allies were able to push 15 miles into the German lines. Approximately 12,000 German troops surrendered and German leaders realized they would soon have to bargain for peace.

September 26 – Meuse-Argonne offensive launched by American and French troops.

September 27 – Hindenburg line breached by British troops.

November 9 – German emperorKaiser Wilhelm II abdicated.

November 11 – Armistice signed ending the war.