The monarch of England during the English Civil War (1642-1651) was King Charles I. His reign was marked by tensions between the monarchy and Parliament, primarily over issues of governance, taxation, and religious authority. Charles's attempts to impose royal prerogatives, such as taxation without Parliament's consent, escalated conflict, leading to a series of armed confrontations. Ultimately, this struggle resulted in his trial and execution in 1649, marking a pivotal moment in English history. The Civil War ended with a brief period of republican rule under Oliver Cromwell, fundamentally altering the relationship between the monarchy and Parliament.