On this anniversary date of King Charles I’s beheading, the two-years-dead corpse of the late Lord Protector Oliver Cromwell was hung in chains at Tyburn and then beheaded, along with the bodies of John Bradshaw and Henry Ireton. The great-great-grandnephew of ruthless Tudor pol Thomas Cromwell rose higher than any English commoner, high enough to be offered the very crown he had struck off at Whitehall. Oliver Cromwell declined it in sweeping Puritan rhetoric just as if he hadn’t spent weeks agonizing over whether to take it. “I would not seek to set up that which Providence hath destroyed and...