World War I involved two major coalitions: the Allies (or Entente Powers) and the Central Powers. Allies (Entente Powers):

• France
• Russia (until 1917, when it withdrew after the revolution)
• British Empire (including dominions and colonies such as Canada, Australia, New Zealand, India, South Africa)
• Italy (joined in 1915)
• United States (joined in 1917)
• Japan
• Other associated members included Serbia, Belgium, Montenegro, Portugal, Romania, Greece, Cuba, Panama, Siam, Liberia, China, Brazil, and several Central American countries like Guatemala, Nicaragua, Costa Rica, Haiti, and Honduras

Central Powers:

• Germany
• Austria-Hungary
• Ottoman Empire (Turkey)
• Bulgaria (joined in 1915)

The war was triggered by the assassination of Archduke Franz Ferdinand of Austria-Hungary in 1914, which escalated tensions among these powers

. The conflict was fought mainly in Europe and the Middle East but also involved colonies and territories worldwide due to the global empires of the involved nations