Editing First World War (section)

=== War at sea and United States entry ===

Britain used its naval strength to blockade Germany and restrict imports. The German High Seas Fleet challenged the British Grand Fleet at the [[Battle of Jutland]] from 31 May to 1 June 1916. The battle caused heavy losses but did not end British control of the North Sea.

Germany relied increasingly on submarines to attack shipping bound for Allied ports. The sinking of the passenger ship ''Lusitania'' on 7 May 1915 damaged relations with the [[United States]]. Germany resumed unrestricted submarine warfare on 1 February 1917, allowing U-boats to attack ships without warning in designated waters.

The United States declared war on Germany on 6 April 1917. German submarine policy and the [[Zimmermann Telegram]] influenced the decision. American troops arrived in increasing numbers during 1918 and strengthened the Allied position on the Western Front.