Lambert, John, 1619–83, English parliamentary general. He fought in the first civil war (1642–46) and assisted Henry Ireton in drawing up the Heads of the Proposals in 1647. In 1648 he commanded the Army of the North against the Scots in the second civil war and later took part in the Scottish campaigns of 1650–51 and the defeat of Charles II at Worcester. He played a leading role in drafting the Instrument of Government (1653), by which Oliver Cromwell became protector, but broke with Cromwell over the latter's acceptance of the Humble Petition and Advice. At the fall of Richard Cromwell (1659) Lambert defeated a royalist uprising in Cheshire and assisted in dissolving the Rump Parliament. When Gen. George Monck marched south to restore Parliament, Lambert attempted to join him, but his army deserted him. After the Restoration (1660), he was tried for treason and banished to the island of Guernsey.