Without warning a German submarine torpedoes the ocean liner The Lusitania off the south coast of Ireland. 1198 drowned. It sank within 20 minutes.

Germany defended its actions by saying it had warned that any ship entering into the war zone around Britain would be attacked. It was discovered that the ship was carrying 173 tons of war munitions for Britain.

A number of further attacks by Germany against international vessels would eventually cause the US to declare war on Germany, after the US had previously declared its neutrality.