Western Front: This was the main theater of operations, where most of the fighting took place. It was located in France and Belgium, and involved trench warfare and large-scale battles such as the Battle of the Somme and the Battle of Verdun.
Eastern Front: This front was located in Eastern Europe, where the Russian Empire fought against Germany and Austria-Hungary. It involved large-scale battles such as the Battle of Tannenberg and the Brusilov Offensive.
Italian Front: This front was located in Northern Italy, where Italy fought against Austria-Hungary. The fighting took place in the Alps and involved mountain warfare.
Balkan Front: This front was located in the Balkans, where the Ottoman Empire fought against Russia, Serbia, Montenegro, and Greece. It involved several campaigns and battles, including the Gallipoli Campaign and the Battle of Salonika.
African Fronts: There were several fronts in Africa, including the East African Campaign, where Britain and Germany fought over control of the German East Africa colony, and the North African Campaign, where Britain and Italy fought for control of Egypt and Libya.
Middle Eastern Fronts: There were also several fronts in the Middle East, including the Mesopotamia Campaign, where Britain fought against the Ottoman Empire for control of Iraq, and the Sinai and Palestine Campaign, where Britain fought against the Ottoman Empire for control of the Sinai Peninsula and Palestine.
Naval Warfare: Naval battles and engagements took place in various oceans, including the North Sea, the Atlantic Ocean, and the Mediterranean Sea.