From the 1895 general election the Liberal Unionists were in coalition with the Conservative Party, under Chamberlain's former opponent Lord Salisbury. In that government Chamberlain promoted the Workmen's Compensation Act 1897. He served as Secretary of State for the Colonies, promoting a variety of schemes to build up the Empire in Asia, Africa, and the West Indies. He had major responsibility for causing the Second Boer War (1899–1902) in South Africa and was the government minister most responsible for the war effort. He became a dominant figure in the Unionist Government's re-election at the "Khaki Election" in 1900. In 1903, he resigned from the Cabinet to campaign for tariff reform (i.e. taxes on imports as opposed to the existing policy of free trade with no tariffs). He obtained the support of most Unionist MPs for this stance, but the Unionists suffered a landslide defeat at the 1906 general election. Shortly after public celebrations of his 70th birthday in Birmingham, he was disabled by a stroke, ending his public career.