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What happened at the Battle of Naseby in 1645?

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Painting of the Battle of Naseby shows cavalry and infantry clashing, with soldiers on horseback leading a charge and fallen fighters on the ground amid the chaos of battle. — English Civil Wars *Battle of Naseby*, by an unknown artist. The victory of the Parliamentarian New Model Army, under Sir Thomas Fairfax and Oliver Cromwell, over the Royalist army, commanded by Prince Rupert, at the Battle of Naseby (June 14, 1645) marked the decisive turning point in the English Civil War.

The Battle of Naseby, fought on June 14, 1645, was the decisive engagement of the first phase of the English Civil Wars. It pitted the newly formed, professional New Model Army—led by Sir Thomas Fairfax and Oliver Cromwell—against the Royalist forces commanded by King Charles I and Prince Rupert.12

The battle began with a tactical error by Prince Rupert, who attacked after mistaking a Parliamentary repositioning for a retreat. While Rupert’s cavalry successfully broke the Parliamentary left flank, they rode off in pursuit, leaving the Royalist infantry vulnerable. Cromwell exploited this blunder by leading a disciplined charge that broke the Royalist left and then crushed their center.1

The victory was overwhelming for Parliament, resulting in 1,000 Royalist deaths and 5,000 captures, compared to only 400 Parliamentary losses. The defeat shattered Royalist hopes, led to the capture of incriminating letters detailing Charles's plans to involve foreign armies, and ultimately forced the King to surrender to Scottish allies in 1646.12