George was generally supportive of Austria in the Diet of the German Confederation. As the Austro-Prussian War started, the Prussian government sent a dispatch on 15 June 1866 demanding that Hanoverian troops submit to their authority or face war. Despite previously having concluded that Hanover could not win an armed confrontation with Prussia, George remained protective of his throne and refused the ultimatum. Contrary to the wishes of the parliament, Hanover joined the Austrian camp in the war. As a result, the Prussian army occupied Hanover and the Hanoverian army surrendered on 29 June 1866 following the Battle of Langensalza, the King and royal family having fled to Austria. The Prussian government formally annexed Hanover on 20 September 1866, despite the King of Prussia, William I, being a first cousin of King George V of Hanover; their mothers were sisters. The deposed King never renounced his rights to the throne or acknowledged Prussia's actions. From exile in Gmunden, Austria, he appealed in vain for the European great powers to intervene on behalf of Hanover. From 1866 to 1870, George V maintained the Guelphic Legion partially at his own expense.