* Europe: The main theaters of World War I were in Europe, including the Western Front (France and Belgium), the Eastern Front (Russia and Germany), the Italian Front (Italy and Austria-Hungary), the Balkan Front (Serbia, Bulgaria, and Greece), and the Gallipoli Campaign (Turkey).
* Africa: There were military campaigns in Africa, such as the German East Africa Campaign and the North African Campaign.
* Asia: The Middle Eastern Front saw conflicts between the Ottoman Empire and the Allied Powers, including the Gallipoli Campaign and the Mesopotamian Campaign.
World War II (1939-1945):
* Europe: World War II began in Europe with the German invasion of Poland in 1939. The war spread across the continent, involving most European countries and resulting in widespread destruction and loss of life.
* Asia: The Asia-Pacific region was also a major theater of war during World War II. The conflict included the Japanese invasion of China, the Pacific War between Japan and the United States, and the Burma Campaign.
* Africa: North Africa was a key battleground during World War II, with major campaigns such as the Battle of El Alamein and the invasion of Algeria and Morocco.
* Middle East: The Middle East was also involved in the conflict, with campaigns such as the Battle of Tobruk and the Anglo-Soviet invasion of Iran.