Sir Thomas Fairfax

October 23, 1642 · 3,000 total casualties

Edgehill exposed the strengths and weaknesses of both armies: Rupert's cavalry was devastating but undisciplined, while Parliament's infantry proved more stubborn than expected. The battle's inconclusive result meant the war would be long. Cromwell, a relatively minor cavalry captain at Edgehill, reportedly told his cousin that the Royalists had better men — and that Parliament needed to find men of 'a spirit that is likely to go on as far as gentlemen will go.'

June 30, 1643 · 2,500 total casualties

Adwalton Moor was the high-water mark of Royalist power in the North of England. The victory gave Charles control of England's most populous and prosperous region outside London, and seemed to tip the war decisively in his favor. It prompted Parliament to urgently negotiate the Solemn League and Covenant with Scotland — bringing a Scottish army into the war on Parliament's side, which would prove decisive at Marston Moor the following year.

June 14, 1645 · 6,100 total casualties

Naseby was the decisive battle of the English Civil War. The King lost his best infantry — approximately 5,000 were captured — along with his artillery, his baggage train, and his secret correspondence. He would never again field a comparable force. The battle was the New Model Army's finest hour: trained, paid, and commanded by merit rather than birth, it had proven itself the finest military force England had ever produced. The publication of Charles's captured letters, showing him seeking Irish Catholic and foreign help, shattered whatever remained of moderate Royalist opinion.

April 27 – June 24, 1646 · 600 total casualties

The fall of Oxford effectively ended the First Civil War. With the capital of his cause in Parliamentary hands and himself a prisoner of the Scots, Charles had no military options left. The nine weeks between Charles's self-surrender and Oxford's fall were spent in the political maneuvering that would define the postwar period: Charles was already playing Parliament against the Scots against the Army, the triangular negotiation that would eventually lead to the Second Civil War and his own execution.