The conflict between the king and the Parliament was inevitable and two opposing camps were formed in the country:
The Royalists and the Parliament

The first conflict between king and Parliament during Stuart monarchs had started with James I. But his disagreements with Parliament were temporary. His son Charles I had serious arguments with Parliament and he had also dissolved Parliament two times and then he assumed the Parliament that is called “Long Parliament”.
Civil war is also called the Great Rebellion. It was precipitated by the War of Bishop with Scotland. There were two opposing sides. The first were the Royalists, or we can call them cavaliers. At the other hand were supporters of Parliament called also Roundheads. This was the time when each Englishman had to decide for Royalists or Parliament. Most of them did not wanted to make decision. Puritans and Anglicans had started to sign the Agreement of neutrality. Soon after these neutralists found out that the armies behave to them as to the enemies. So they had to decide to one side. Cathedral towns, Wales and the North and West of England had been standing up for bishops and either for king. London, South and East had been standing up for Parliament and they had there their main seat.
Parliament was able to levy taxes, but for ready money the king was dependent on his supporters.
At the beggining of the war no one of the Parliament wanted to overthrow Charles I. They just wanted to get rid of his bad advisors and also supporters.
Charles I raised his standard at Nottingham. Although unchecked at Edgehill he abandoned and advance on London when confronted by a Parliamentary force at Turnham Greem. Then he went to Oxford, which became his military seat. In 1643 the Royalists at Adwalton Moor won control at almost all Yorkshire, while Parliament was victorious at Winceby and took Lincoln. Parliament in the Solemn League and Covenant bought Scottish military aid, the king made peace with the Irish thereby freeing troops for deployment in Britain. Despite the Parliamentary victory at Marston Moor, in general the Royalist operations of 1644 were the more successful. King and also Parliament had wanted to reach Scots but they wanted to make Presbyterian England. But king were Anglican and Parliament was either hesitating. In 1643 Parliament had signed with Scotland COVENANT.
One of the best soldiers was Oliver Cromwell. He was strict Puritan.