In the 1868 General Election Campbell-Bannerman was elected as Liberal MP for Stirling. After the 1884 General Election the Prime Minister, William Gladstone, appointed Campbell-Bannerman as his Chief Secretary for Ireland, but he did not enter the Cabinet until he became War Secretary in 1886.
Campbell-Bannerman was not a very good parliamentary orator but had a reputation as an efficient political operator and in 1898 became leader of the House of Commons. Campbell-Bannerman opposed the Boer War and advocated comprehensive social reforms and in doing so established himself as one of the most important figures on the progressive wing of the party.
When Arthur Balfour and his Conservative government resigned in 1905, Edward VII invited Campbell-Bannerman to form a government. He accepted and in the 1906 General Election that followed the Liberal Party had a landslide victory. Important legislation passed during the first few months of office included the Trades Disputes Act and the Provision of School Meals Act.
Henry Campbell-Bannerman became very ill and on 4th April 1908 he was forced to resign and died eighteen days later.