1917
Austria-Hungary declared war on Serbia on 28 July 1914, Russia declared war on Austria-Hungary, Germany declared war on Russia and then on France, then the UK declared war on Germany on 4 August. Various other countries joined the war on either side, but despite provocation by German actions the USA adopted a policy of non-intervention until early 1917 after renewed German attacks and an attempted plot with Mexico, at which, on 6 April 1917, Congress approved joining the Allied Powers against Germany and the other Central Powers. On 11 November 2018 the Allies signed an armistice with Germany to end the hostilities.