Who they were
A Puritan gentleman and MP, Cromwell built the disciplined New Model Army cavalry and helped defeat Charles I. He signed the king’s death warrant in 1649, then crushed resistance in Ireland and Scotland — his 1649 campaign in Ireland, including the storming of Drogheda, is remembered there for its brutality — and in 1653 dissolved Parliament to rule as Lord Protector.
What they did
His Protectorate gave England stable if authoritarian government, religious toleration for most Protestants, and renewed military power abroad.
Legacy
The monarchy was restored two years after his death, and his body was posthumously exhumed and displayed. Cromwell is judged very differently as regicide and dictator or as a defender of liberty and Parliament — a debate that continues.