Prince Rupert of the Rhine

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.'

September 20, 1643 · 2,600 total casualties

First Newbury was Parliament's first major defensive success. Essex had relieved Gloucester under the King's nose and then fought his way back to London — a major propaganda and strategic victory. The battle also marked the death of the young Lord Falkland, Secretary of State and one of the most admired moderate figures of the age, who rode deliberately into the fighting — apparently seeking death at the prospect of his country's ruin.

July 2, 1644 · 5,650 total casualties

Marston Moor destroyed Royalist power in the North of England permanently. The Earl of Newcastle, humiliated, took ship for the Continent and never returned. Prince Rupert's legend was badly dented. Most importantly, it was the battle that made Cromwell's national reputation: his disciplined cavalry, which unlike Rupert's horse rallied after their charge rather than pursuing fleeing enemies, proved the decisive factor. A Scottish officer reported that Cromwell had said 'God made them as stubble to our swords' — and the phrase captured something real about his iron Calvinist faith and military genius combined.

August 21 – September 2, 1644 · 6,250 total casualties

Lostwithiel demonstrated that the Parliamentary war effort under the old nobility was faltering. Essex had walked into a trap and lost his army. The disaster accelerated Parliamentary debates about military reorganization and the creation of a professional national army. Within months the Self-Denying Ordinance would remove MP's from field command and clear the way for the New Model Army under Thomas Fairfax.

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.