The Battle of Fontenoy was fought at Fontenoy in the Austrian Netherlands on May 11, 1745, during the French forces under Hermann Maurice, Count de Saxe (the Maréchal of Saxe, an illegitimate son of King Frederick Augustus I of Poland) were besieging Tournay. An Anglo-Dutch-Hanoverian army under the Duke of Cumberland advanced to the relief of Tournay, with the British forces attacking French positions uphill. The French lost 5000 men, while the British lost 9000 men, an effective defeat for Cumberland's forces.

While Cumberland's courageous attack on the superior positions of the French army was unsupported by his allies and his forces had to retreat, the Duke accounted well for himself.

The brigade which he commanded in the attack included the Scottish Highland Black Watch regiment. Although they had joined the British forces on the continent in 1743, this was their first battle. Their courageous determination to press the attack greatly impressed the Duke of Cumberland, and they introduced the then novel technique of hurling themselves to the ground when a volley was fired at them, then leaping to their feet and firing back. This "Highland way" of fighting may have been learned in their previous role of policing the highlands, but while they were away the Jacobite Rising got under way and in the autumn of 1745 the Black Watch was moved to the South of England for defence against possible French invasion while the British were preoccupied further north.

(This should not be confused with the two battles of Fontenay, which occurred at a different location, in 841 and 1944.)