He held the office of Secretary at War between 1839 and 1841, and served as Paymaster-General and a member of the cabinet in Lord Palmerston's first government from 1846 to 1848.
Macaulay is renowned for his historical works, including The History of England from the Accession of James II (1848–1855) and his biographies of Samuel Johnson and William Pitt the Younger.
As a politician, he advocated for social reform, the abolition of slavery, and the expansion of education and government services. Macaulay's writings and political activities significantly influenced the development of British society and politics in the 19th century.