In 1621, Sir Richard remarried, this time to Grace Rolle (1606–1655); their four sons included John Carew, who signed the death warrant for Charles I, and was executed for treason, in October 1660.

[3] Richard Carew was a moderate Puritan, who was more interested in education, inventions, and breeding cats; in August 1641, he purchased a baronetcy, a method used by Charles I to raise money.

"[2] When the First English Civil War began in August 1642, Carew was one of the relatively few members of the Cornish gentry who openly supported Parliament, and was appointed to numerous committees as a result.

Many went to war in 1642 expecting a single, decisive battle; by 1643, it was clear this was incorrect, and Parliamentarians like Carew whose estates lay in occupied territory faced financial ruin.

In August, he ordered his men to open fire on a Parliamentarian warship entering harbour; they refused, and he allegedly escaped lynching only after the ship's captain intervened on his behalf.

In August 1644, Parliament established a military tribunal to try those suspected of treachery; in November, Carew was sentenced to death, along with the former commander of Hull, Sir John Hotham, and his son.