The Siege of Gibraltar was a military action during the War of the Spanish Succession during which the fortress of Gibraltar was captured by allied British and Dutch forces after a three days’ siege, on July 24, 1704. The attack was carried out by a brigade of Dutch and British Marines, 1800 strong, under the command of Prince George of Hess-Darmstadt.

The capture was made in the interests of Charles, archduke of Austria, but Sir George Rooke, the British admiral, on his own responsibility caused the British flag to be hoisted, and took possession in name of Queen Anne, whose government ratified the occupation.

A great number of the inhabitants of the town of Gibraltar abandoned their homes rather than recognize the authority of the invaders. The Spaniards quickly assembled an army to recapture the place, and a new siege opened in October 1704 by troops of France and Spain under the marquess of Villadarias.

The Marine brigade, still under the command of the British admiral, Sir John Leake, and the military governor, Prince George of Hesse-Darmstadt (who had commanded the land forces in July), and reinforced shortly before by a further 400 Royal Marines, held the fortress against repeated attacks.

A notable incident during the siege was the attempt made by 500 French and Spanish volunteer grenadiers to surprise the garrison on October 31. Captain Fisher of the Marines with 17 of his men successfully defended the Round Tower against their assault. A contemporary report of this noted defence says, "Encouraged by the Prince of Hesse, the garrison did more than could humanly be expected, and the English Marines gained an immortal glory".

On March 9, 1705, the French marshal de Tessé, who had replaced Villadarias, gave up the siege and retired.