Answer:
The February Revolution of 1917
Explanation:
World War I (1914-1918) was a major global conflict that pitted France, the United Kingdom, Russia and Italy against Germany, Austria-Hungary and the Ottoman Empire. While the United States remained neutral until 1917, it became a major supplier to the United Kingdom and its allies.
American public opinion was against getting involved in the war, considering it an intra-European conflict. However, the Zimmerman telegram, which tried to convince Mexico to ally itself with Germany against the United States, and the sinking of several US ships by German submarines, gradually shifted public opinion.
However, United States president, Woodrow Wilson, was very reluctant to fight on the same side as the Russia, which was an absolutist monarchy. But the Russian Revolution of February 1917 dethroned Tsar Nicholas II, and a republican Russian Provisional Government was established. This allowed president Wilson to go before Congress and ask for war against Germany and its allies, which were considered authoritarian monarchies. In his view, the United States should get involved in a war that would "make the world safe for democracy". The United States declared war against Germany on April 6, 1917.
