U.S. Entry into World War I

U-boats begin sinking merchant ships

Jan 1, 1915

After finding contraband on British ships, U-boats would sink the merchant ships

Great Britain Mounts guns on merchant ships

Feb 3, 1915

British merchant ships begin sinking U-boats instead of allowing German inspectors on board.

U-boats begin unrestricted submarine warfare

Feb 9, 1915

Germany allows U-boats to sink British merchant ships without warning.

U-boat sinks Lusitania

May 7, 1915

Germany agreed to stop sinking passenger ships without warning.

May 18, 1915

Battle of Jutland

Mar 4, 1916

Sussex Plege

Mar 24, 1916

Sussex sunk - Americans threatened Germany and Germany promised to stop sinking ship without warning

Germany announced unrestricted submarine warfare would resume

Jan 31, 1917

Germany hoped to end the war in Europe before U.S. could join the fighting.

Zimmermann Note uncovered

Feb 1, 1917

Broke off Dplomtic Ties with Germany

Feb 3, 1917

U.S. armed merchant ships

Feb 6, 1917

Russian Revolution - Democratic government takes over

Mar 4, 1917

Germany sank 3 ships

Mar 16, 1917

U.S. Declares War on Central Powers

Apr 6, 1917