The Second Siege of Bristol of the First English Civil War lasted from 23 August 1645 until 10 September 1645, when the Royalist commander Prince Rupert surrendered the city that he had captured from the Parliamentarians on 26 July 1643. The commander of the Parliamentarian New Model Army forces besieging Bristol was Lord Fairfax.

King Charles, almost stunned by the suddenness of the catastrophic loss of Bristol, dismissed Rupert from all his offices and ordered him to leave England.