Richard Cromwell entered national politics under the regime established by his father Oliver. He served in the Protectorate Parliaments of 1654 and 1656, became chancellor of Oxford University in 1657, and received places on the council and in the new upper parliamentary chamber. These appointments gave him neither his father's experience nor authority among senior army officers.

When Oliver died in September 1658, Richard was proclaimed lord protector of England, Scotland, and Ireland. The succession initially attracted broad acceptance, including recognition abroad. He relied on civilian advisers such as John Thurloe and hoped to maintain the constitutional arrangements of the Protectorate. Financial problems, unpaid soldiers, and divisions among army leaders nevertheless threatened the settlement from its beginning.

Richard summoned Parliament in January 1659 to obtain revenue and political support. Although the Commons recognized his position, arguments over the upper chamber and the army's status exposed divisions between civilian politicians and military officers. Republican opponents encouraged resistance to the Protectorate, while the officers feared parliamentary control and possible prosecution for earlier conduct. Richard negotiated but lacked a reliable armed following to enforce his decisions.

Under military pressure he dissolved Parliament in April. The officers then lost control of the political outcome as demands grew to restore the Rump Parliament, which had been expelled in 1653. It returned in May, and Richard's renunciation of the protectorship was read later that month. His rule had lasted less than nine months. Burdened by debts, he left England in 1660 and spent about twenty years abroad before returning to live quietly at Cheshunt. He died in 1712 without returning to politics. His collapse exposed the unresolved relationship between Parliament and the army, rather than merely the personal weakness suggested by his nickname “Tumbledown Dick”.