Western Front
* Battle of the Marne (1914): One of the first major battles of the war, it resulted in a French victory and halted the German advance on Paris.
* Battle of the Somme (1916): One of the bloodiest battles in human history, it resulted in over one million casualties.
* Battle of Verdun (1916): Another of the war's bloodiest battles, it was a costly victory for the French.
* Battle of Passchendaele (1917): A British offensive that was ultimately unsuccessful and resulted in heavy casualties.
* Battle of Amiens (1918): A successful Allied offensive that marked the beginning of the end of the war on the Western Front.
Eastern Front
* Battle of Tannenberg (1914): A German victory that resulted in the destruction of two Russian armies.
* Battle of Galicia (1914): Another German victory that resulted in the capture of Lemberg.
* Battle of Przemyśl (1915): A Russian victory that resulted in the capture of a major fortress.
* Battle of Brusilov (1916): A successful Russian offensive that resulted in heavy Austrian losses.
* Kerensky Offensive (1917): A failed Russian offensive that resulted in the collapse of the Russian army.
Other Fronts
* Gallipoli Campaign (1915-1916): An unsuccessful Allied attempt to capture the Gallipoli peninsula from the Ottoman Empire.
* Mesopotamia Campaign (1914-1918): A British campaign to capture Mesopotamia (present-day Iraq) from the Ottoman Empire.
* East African Campaign (1914-1918): A campaign between British, Portuguese, and Belgian forces and German forces in East Africa.
* Sinai and Palestine Campaign (1915-1918): A British campaign to capture Palestine and Sinai from the Ottoman Empire.
* Italian Front (1915-1918): A series of battles between Italian and Austro-Hungarian forces.