The city of Hull had a large store of weapons and both Parliament and King Charles I wanted to take control of it. Parliament had wanted the arms to be shipped to the Tower of London for, they said, use in Ireland against the rebels, but Charles refused. Charles sent his son Prince Rupert to Hull on the 22nd of April and he had been welcomed. When Charles arrived a day later the Governor of Hull, Sir John Hotham a supporter of Parliament, refused him entry fearful that the King would take the arms by force.

A sum of two thousand pounds was demanded by Prince Rupert from the people in Leicester to save their town from being robed. They only paid 500 pounds and complained to King Charles. The king was unhappy with the Princes' actions but the money was not handed back.

Royalists led by Prince Rupert defeated a Parliamentarian force emerging from Powick Bridge that crossed the River Teme near Worcester. The Royalists attacked before the Parliamentarians had time to organise themselves, driving them back across the bridge. Prince Rupert's reputation as a formidable commander was made at this engagement.

The Royalists led by Charles moved on Banbury. The town surrendered without a fight and the Prince Rupert took control of the nearby Broughton Castle.

In early November Charles took Reading while Prince Rupert was attacking Windsor Castle. Prince Rupert's efforts failed so he turned his attention south to Brentford dealing the Parliamentary forces a heavy blow. Charles' next objective was to take London but the Londoners put an army together. When the Londoners' army was reinforced with the army of the Earl of Essex there was a standoff. The Royalist and Parliamentary armies faced each other at Turnham Green but Charles was outnumbered and chose to withdraw.

Prince Maurice, younger brother of Prince Rupert, defeated Sir William Waller at Ripple Field near Worcester.

The Royalists under the command of Prince Rupert were determined to retake Lichfield Cathedral. Prince Rupert had a mine dug beneath the walls that surrounded the Cathedral and packed it with explosives. Before he blew the mine he had given those inside the walls a chance to surrender but they refused. The wall was breached and after a fight the Royalists retook control. This is generally thought to be the first time explosives were used in a mine in this way. The Cathedral suffered substantial damage at this time and was not fully restored for hundreds of years.

Prince Rupert and his army had crossed the Pennines and was heading for York to rescue the city from the Parliamentary siege.

The battle of Marston Moor. With the arrival of Prince Rupert, the Parliamentarian forces led by generals Leven, Fairfax and Manchester abandoned the siege of York and headed south. Rupert followed and attacked the rear of the column forcing the fleeing army to stop. The Parliamentarians held the higher and tactically better position on Long Marston Moor. The Duke of Newcastle and his Royalist men joined Prince Rupert to create an army of around eighteen thousand men while the Parliamentarians had a force of around twenty eight thousand men and had better artillery. Late in the day the fighting began with an attack by Leven and Fairfax in the centre. The attack did not go well for the Parliamentarians and Leven and Fairfax left the battlefield. Whan all seemed lost a cavalry unit commanded by Oliver Cromwell on the left of the field attacked the Royalists and gained the upper hand. The Royalists were defeated leaving some three to four thousand of their men dead.

The Battle of Naseby. Sir Thomas Fairfax and the New Model Army caught the King at Naseby Field in Northamptonshire. Cromwell joined Fairfax and the combined Parliamentary force consisted of some 14,000 men while the King and Prince Rupert had around half that number. The King had a better position on the battlefield and had more experienced soldiers while some of the Parliamentary men were raw conscripts. For the Parliamentarians, Skippon commanded the infantry, Cromwell commanded the Ironsides to the left and to the right Ireton commanded his men. Both Skippon and Ireton were injured in the battle. Ireton was captured but managed to escape. Cromwell's Ironsides routed the Royalist army and the battle was won. King Charles was defeated. King Charles and his cavalry escaped to Leicester but he left has baggage train behind unprotected. Large amounts of the King's and his supporters money was captured by the Parliamentarians along with the King's personal letters.

Fairfax surrounded the city of Bristol which was held by Prince Rupert and several thousand Royalists soldiers. After a short siege Fairfax ordered an early morning assault on the city. Bristol fell to the Parliamentarians.