On 4 August, Britain (and its Empire) entered the World War with H. H. Asquith of the Liberal Party as British prime minister. Britain's reasons for declaring war were complex: the Treaty of London of 1839 had committed it to safeguard Belgium's neutrality, and the strategic risk posed by German control of the Belgian coast was unacceptable. Asquith's Liberal government was brought down in May 1915, due in particular to a crisis in inadequate artillery shell production and the failure of the Gallipoli Campaign in the Dardanelles.