How did President Wilson react to Germany's use of submarines?

President Wilson reacted by asking the Congress to declare war on Germany.

Narrowly re-elected in 1916, Wilson's second term centered on World War I. He based his re-election campaign around the slogan "he kept us out of the war," but U.S. neutrality was challenged in early 1917 when the German government proposed to Mexico a military alliance in a war against the U.S. When Germany began unrestricted submarine warfare, among other things sinking the Lusitania without warning, as well as any merchant ship its submarines could find regardless of the country it belonged to, Wilson asked Congress to declare war in April 1917.