I’m in Northamptonshire on my way to a battlefield where England changed from being a monarchy to a republic … Members of parliament were in armed conflict with their king. Rob Bell, Britain’s Lost Battlefields s1e5: Naseby
At the start of 1640s Charles I was King … There was growing disapproval of the King.
At around 3.30 p.m. as the Royalist foot soldiers lay down their arms, King Charles I and his lifeguards fled the battlefield. ibid.