Campbell-Bannerman held junior ministerial posts in the War Office and Admiralty between 1871and 1884, then became Chief Secretary for Ireland in 1884 with Cabinet rank. After serving as Secretary of State for War from 1886-95, he became leader of the Liberal party in the House of Commons in 1899, at a time when the party was disunited on policy with regard to the Boer War (1899-1902).
The Liberals returned to power in 1905, with Campbell-Bannerman forming a minority Government and immediately opting for a General Election, which was won in a landslide on the issue of free trade.
His period of office as Prime Minister lasted only until 1908, as ill-health forced him to resign the post in April, dying later that month.
Campbell-Bannerman was an effective minister and successfully managed the rival factions in the Liberal Party around the turn of the century, commanding enthusiastic support and respect.