The Triennial Act 1640, also known as the Dissolution Act, was an act passed on 15 February 1641, by the English Long Parliament, during the reign of King Charles I. The act required that Parliament meet for at least a fifty-day session once every three years. It was intended to prevent kings from ruling without Parliament, as Charles had done between 1629 and 1640. If the King failed to call Parliament, the act required the Lord Chancellor to issue the writs, and failing that, the House of Lords could assemble and issue writs for the election of the House of Commons. Clause 11 was unusual because it explicitly stated that this bill would receive royal assent before the end of the parliamentary session. At that time, bills did not customarily gain royal assent until after the end of the session. There was a risk that, if this Clause 11 had not been present, the Act might not have come into force until the next parliament.