He endured numerous failures throughout his career, including the Gallipoli Campaign during the First World War and his political exile in the interwar years, yet he remained steadfast in his belief in his vision and abilities. His exploits in early campaigns such as Cuba, India, and Sudan and during the Boer War (1899–1902), in addition to, the First World War (1914–1918) offer glimpses into his courage, resourcefulness, and determination, traits that would later define his leadership as Britain's wartime prime minister. Churchill's military involvement resumed during the First World War when, after the Gallipoli campaign debacle, he resigned as First Lord of the Admiralty and sought to redeem his reputation.