Oliver Cromwell was an English statesman and military leader who served as Lord Protector of the Commonwealth of England, Scotland, and Ireland from 1653 until his death in 1658. He was one of the chief architects of the English Civil War, which led to the overthrow and execution of King Charles I. After the war, Cromwell emerged as one of the leaders of the Commonwealth and, as Lord Protector, he implemented a number of radical political and religious reforms.

Cromwell was born into an gentry family in Huntingdon, England in 1599. He attended Cambridge University but did not graduate. After university, he managed his family's estates and dabbled in local politics. Cromwell's views on religion, politics, and the role of the monarchy were heavily influenced by Puritanism.

In the 1640s, Cromwell became increasingly involved in national politics, and he served as a member of the Long Parliament. He opposed the policies of King Charles I and the Catholic Church and was appointed commander of the parliamentary army in 1645. Under his leadership, the parliamentary army emerged victorious in the English Civil War, and Charles I was executed in 1649.

After the war, Cromwell played a leading role in the Commonwealth government and was appointed Lord Protector in 1653. As Lord Protector, he established a Commonwealth army and a powerful navy, and he implemented a number of social and religious reforms. He also oversaw the conquest of Ireland and Scotland, and he sought to create a Puritan-style theocracy.

Cromwell died of natural causes in London in 1658. He was buried in Westminster Abbey, but after the Restoration of Charles II in 1660 his body was exhumed, hanged and buried at Tyburn, London>

As Lord Protector of England, Scotland and Ireland, Oliver Cromwell implemented a number of political and religious reforms. He sought to create a Puritan-style theocracy and imposed strict moral codes on the population. He dissolved the Long Parliament, and established a new governing body called the "Barebone's Parliament" made up of nominees of his own.

He also established a powerful Commonwealth army and navy. He used this military power to invade and conquer Ireland and Scotland, in what were known as Cromwell's Irish and Scottish Wars. These invasions were brutal and left a lasting impact on the native population, causing mass displacement and deaths.

In terms of economic policy, Cromwell encouraged the development of industry and commerce, and he sought to promote the interests of the middle class. He also abolished feudal land tenure and encouraged the growth of smallholdings.

Cromwell's rule was marked by an intolerance of religious dissent, particularly among Anglicans and Catholics, and his regime persecuted those who did not conform to his Puritan beliefs. He dissolved the monasteries and introduced strict censorship of the press and other forms of communication.

Cromwell's rule ultimately ended with his death in 1658, and his period of rule was known as the Commonwealth. The country returned to a monarchy, with Charles II as the king after Cromwell death.

It's worth noting that Cromwell's legacy is still debated and remain controversial, some view him as a great statesman, who brought order and stability to England and also as a religious reformer, while others see him as a dictator who imposed his will on the population, and his military campaigns in Ireland and Scotland had a disastrous effect on the population.