Answer:
The United States initially remained neutral when Britain asked America to join World War I. President Woodrow Wilson was re-elected in 1916 on a platform of neutrality and peace, and he hoped to keep the United States out of the war.
However, American sentiment began to shift as the war continued and evidence of German aggression and atrocities mounted. In 1917, Germany resumed unrestricted submarine warfare, which included attacks on American ships. The Zimmermann Telegram, in which Germany proposed an alliance with Mexico against the United States, was also intercepted and made public. These events, along with pressure from British and French leaders, led Wilson to ask Congress to declare war on Germany on April 2, 1917.
The United States officially entered the war on April 6, 1917, and began sending troops and supplies to Europe to aid the Allied powers. The U.S. contribution was significant, providing crucial support that helped to turn the tide of the war in favor of the Allies. The U.S. involvement also helped to shape the post-war world, with Wilson playing a key role in negotiating the Treaty of Versailles and advocating for the establishment of the League of Nations.
Overall, while the United States initially remained neutral when Britain asked America to join World War I, American sentiment eventually shifted and the U.S. became a major player in the conflict.