On October 24, 1817, Prime Minister Arthur Wellesley (later changed to Arthur Wellington) led a revolution against the British monarchy. George IV was killed, his successor William IV fled Britain, and Wellesley declared himself Chancellor of the new Commonwealth of Great Britain. Lamb, always the moderator, attempted to negotiate a peace with Wellesley the day after. He pleaded with the new Chancellor to change course, and work to put the country back together. After several hours of discussion and arguing, Lamb left thinking he had talked Wellesley into calling off the army and mobs.
Later that night, William Lamb was arrest (most of Parliament was arrested within a 24 hour period after the revolution) and held captive by the revolutionary regime. He was executed by firing squad a week later on November 1st as an enemy of the regime and the proletariat; he was 38. Although he had a relatively short career in politics, William Lamb has become a martyr of the movement to restore the British monarchy. His execution has been used as an example of Wellesley's bloodthirstiness and his lack of care for human life. After his death, Lamb was honored by the governments of multiple countries.