He was a strong character who was a natural leader, rising from modest origins to lead the country.
Oliver Cromwell was instrumental in organising and leading the New Model Army. When the new Republic was in turmoil, Cromwell was the natural choice to lead it and bring together the divided factions: a nearly impossible task. As Lord Protector and ruler of England, Scotland and Ireland, he rose to enjoy the powers, if not the title, of king.
He tried to rule with toleration and moderation.
He aimed to heal the divisions in the country, not to rule for the benefit of just one side. He allowed Catholic, Protestant and Jew to worship according to their conscience. His aim was for a programme of Christian evangelism alongside a broad religious toleration.
He tried to be just and fair.
He lobbied for parliament to develop strategies for long-term constitutional settlement. He introduced reforms to make the legal, judicial and social systems more humane. He promoted soldiers on their ability not their social status. His policies, although not always successful, aimed to bring the country together rather than to cause more divisions. He had only supported the execution of the king when he saw no other way forward, after Charles refused to abdicate.
Oliver Cromwell re-established England as a leading power in Europe.
With a strong Army and Navy, Oliver Cromwell also looked to raise England's profile abroad.
He was courageous and skillful and cared for his soldiers.
He took care in the training and equipping of his men and maintained tight discipline both on and off the battlefield. He fought alongside his men and his great personal courage led to his great military successes.
He could be ruthless. His actions in Ireland escalated an appalling cycle of violence stretching forward for decades.
The most bitterly controversial events in Oliver Cromwell's life were his sack of Drogheda and Wexford in his Irish campaign, in which hundreds, perhaps thousands, of people died, including civilians. In all, he captured 28 towns and castles on and near the east coast.
He ultimately failed to establish the Republic on a sound footing.
He failed to put in place a strong administration for the Republic, capable of surviving after his death. This resulted in the re-establishment of the monarchy.
The Civil War would still have been won without him.
Parliament could still have won the Civil War and then someone else would have been pushed forward to take the leadership of England.
There was a strong authoritarian side to him.
Government was, he felt, for the people's good, not for what pleased them. He imprisoned political enemies and sometimes acted without parliamentary consent.