Churchill served as First Lord of the Admiralty twice. His first term ran from 1911 to 1915, and his second began in 1939 and lasted until 1940, when he became prime minister.
The First Lord was the political head of the Admiralty and carried ministerial responsibility for the Royal Navy. During Churchill's first tenure, he supported naval modernisation, including the development of faster ships and naval aviation. He also helped prepare the fleet for the First World War, which began in 1914.
Churchill returned to the post at the outbreak of the Second World War under Prime Minister Neville Chamberlain. His appointment reflected his forceful views on naval readiness and the German threat. When Chamberlain resigned in May 1940, Churchill became prime minister while remaining closely associated with the direction of Britain's war effort.