England became the Commonwealth after the English Civil War due to the defeat of the monarchy and the establishment of a republic under the leadership of Oliver Cromwell. The Commonwealth was created as a way to replace the traditional monarchy with a government based on parliamentary rule and republican principles. It was seen as a way to create a more democratic and fairer society by limiting the power of the monarchy and giving more power to Parliament. This period also saw the rise of Puritan and religious influence in England, with Cromwell's government promoting a strict moral code and pushing for more religious freedom.
