The Battle of Dunbar (3 September, 1650) was a battle of the Third English Civil War. The Parliamentary forces under Oliver Cromwell defeated Charles Stuart's Scottish army commanded by David Leslie.

After defeating a Scottish invasion of England at the Battle of Preston, an English army of 16,000 men had invaded Scotland on 22 July 1650 and laid siege to Edinburgh, but Leslie refused battle and by the end of August the English, exhausted and running out of supplies, were forced to retreat, first to the port of Musselburgh where the sick and wounded were shipped back to England, and then further southeast to Dunbar. By 1 September 11,000 English soldiers were camped to the south of Dunbar, but the Scottish forces, numbering 23,000, had got ahead of them and captured Doon Hill, blocking the road to Berwick-upon-Tweed. Leslie planned to wait on Doon Hill: if the English attacked him up the steep escarpment they would surely lose, and if they refused battle, hunger and sickness would soon reduce them to the point of surrender. But on 2 September the leaders of the Covenanters decided to attack the English the next day, and the Scottish army moved down from the hill to prepare for the battle.

Cromwell pre-empted the Scottish plans by a night attack early on 3 September. Taking the Scottish completely by surprise, the English cavalry broke the Scottish line and routed Leslie's army. 3,000 Scottish soldiers were killed and 10,000 taken prisoner, and the rest scattered in disarray. 5,000 prisoners were marched to Durham Cathedral: more than 3,000 died of starvation, dysentry and typhus, and the survivers were sold into slavery.

The Royalists recovered from the disaster at Dunbar to invade England again in 1651, when they were defeated by Cromwell at the Battle of Worcester.