From first shot to peace: Timeline of WWI

As the world marks 100 years since the fighting stopped, here is a look at some key moments in World War I.

Paper poppies fill a field outside the Menin Gate in Ypres, Belgium. Source: AAP

1914

June 28: Serb teenager Gavrilo Princip kills Austrian Archduke Franz Ferdinand

July 28: Austria-Hungary declares war on Serbia

August 1: Germany declares war on Russia

August 3: Germany declares war on France

August 4: Germany invades Belgium; Britain declares war on Germany

August 23: Japan declares war on Germany

September: Battle of the Marne stops the German advance in France

October 29: Ottoman Empire enters the war

November: Beginning of trench warfare

December 25: Unofficial Christmas Truce

The walls of the Menin Gate bear the names of more than 54,000 World War I soldiers who died before August 16, 1917 and have no known grave. Source: AAP

1915

February: German U-boat campaign marks first large use of submarines in warfare

April: Allied troops land in Gallipoli , Turkey, a defining moment for Australian, New Zealand

April 22: First use of a chemical weapon , chlorine gas, near Ypres, Belgium

May 7: British ship Lusitania sunk by German U-boat

May 23: Italy enters war, against Austria-Hungary

October: Bulgaria joins war, on side of Central Powers

1916

Feb. 21: Battle of Verdun begins

March 9: Germany declares war on Portugal

July 1: Battle of the Somme begins, with first mass use of tanks

August 27: Romania enters war, is invaded by Germany

September 4: British take Dar es Salaam in German East Africa

October: Soldier Adolf Hitler wounded

Dec. 23: Allied forces defeat Turkish in Sinai Peninsula

1917

March: Baghdad falls to Anglo-Indian forces

April 6: United States declares war on Germany

April: Battle for Vimy Ridge , defining moment for Canada

July: Last Russian offensive ends in failure, as revolution nears; inconclusive Battle of Passchendaele in Belgium

October 15: Spy Mata Hari executed by French firing squad

October 26: Brazil declares war, joining Allied Powers

December: Battle of Jerusalem

Paper poppies are placed next to the names of the missing on the wall of the Menin Gate in Ypres, Belgium. Source: AP

1918

March 3: Treaty of Brest-Litovsk ends Russia's involvement in the war on the Eastern Front.

April 21: Legendary German fighter pilot known as the Red Baron shot down and killed near Amiens, France

June: Battle of Belleau Wood , defining moment for US military

July 21: German submarine fires on Cape Cod, only attack on mainland US

Sept. 26: Battle of the Meuse-Argonne begins

October 30: Ottoman Empire signs armistice with Allies

October 31: Dissolution of Austro-Hungarian Empire

November 9: Germany's Kaiser Wilhelm II abdicates

November 11: Germany signs armistice ending the war