After the capture of Gibraltar, the allies expected a counter-offensive, and in early September, it began. Francisco Castillo Fajardo, Marquis of Villadarias, captain general of Andalusia, marched to the isthmus with an army of 4,000 men.

There he set up camp just out of cannon range from Gibraltar while he awaited reinforcements. The marquis had gathered around 7,000 men by late October and planned to build his force to 12,000 before launching an assault.

Prince George of Hesse, who had taken control of Gibraltar after its capture, re-formed the defences around the Rock and organised the 2,000 English and Dutch marines under his command to hold vulnerable areas with relatively few men, which could be reinforced by a reserve force. Nevertheless, he feared his forces would not be able to withstand a simultaneous assault from land and sea such as the one that had brought him to Gibraltar.

On 4 October, these fears appeared to be realised when several French troop ships, escorted by 19 warships, arrived in the Bay of Gibraltar and disembarked 3,000 soldiers at the head of the bay. The soldiers joined the marquis’s men on the isthmus and, three weeks later, most of the French fleet departed; two days after that (26 October), the Spanish forces established their first battery and began firing on George’s most northerly defences while a French raiding party attacked the harbour. Both parties settled down into the siege for the winter; the Spanish bombardment continued and the English and Dutch brought in reinforcements through December and January.

After desertion and disease reduced the strength of the Spanish force, King Louis XIV of France sent Marshal René de Froulay de Tessé to take command of the siege, along with 4,500 French and Irish reinforcements. On 7 February 1705, 1,000 Spaniards and 500 of the French and Irish reinforcements stormed the Round Tower, but suffered heavy losses in an Anglo-Dutch counter-attack. After the French fleet suffered a defeat at the hands of Admiral Sir John Leake at the end of March, the Catholic force began to withdraw and eventually abandoned the siege.

The confederates retained control of Gibraltar.