The siege of Cork begins on September 21, 1690, during the Williamite War in Ireland. It happens shortly after the Battle of the Boyne during James II’s attempt to retake the English throne from King William III. In a combined land and sea operation, the Williamite commander, John Churchill, takes the city and captures 5,000 Jacobites.

After the Battle of the Boyne, William occupies Dublin and the Jacobites retreat to the west of Ireland. William assaults and besieges Limerick in August 1690 but is repulsed. To secure the Jacobite-held ports of Cork and Kinsale on the southern coast, he dispatches a force under John Churchill, then 1st Earl of Marlborough.

Marlborough reaches Cork by sea on September 21, 1690. His English forces are 5,000 strong and he also has at his disposal a fleet which blockades the port of Cork. He captures several of the harbour’s defences, including Fort Camden, and lands troops at Passage West on September 24, before setting up his base at Red Abbey, to the south of the walled city. Approaching from the northern, landward side are 4,000 Danish troops under the Ferdinand Willem, Duke of Württemberg-Neuenstadt.

The Williamites take the forts, such as Elizabeth Fort, which command the hills around Cork and commences a bombardment of the city from the heights. When a breach is opened in the city walls, the city’s garrison opens surrender negotiations, asking to be allowed to leave Cork and join the main Jacobite army at Limerick. Marlborough refuses the request, although Württemberg is in favour of granting the terms.

A few days later, the Williamites mount a joint English-Danish assault of the breach from the south. Henry FitzRoy, 1st Duke of Grafton, is reputedly mortally wounded while leading this assault. After the Williamites reach the walls, the Governor of Cork, Roger McElligott, opens new surrender talks and agrees that the garrison will become prisoners and will surrender their arms and stores. Marlborough accepts and the city surrenders.

In spite of this, the Williamite troops sack the city, do a great deal of damage, looting much property and abusing the Catholic inhabitants. Many civilians are killed before Württemberg and Marlborough restore order.

It remains for the Williamites to take nearby Kinsale, which is strongly defended by two forts, the Old Fort, also known as James’s Fort, and the New Fort or Charles Fort. Marlborough assaults these fortifications but is unable to take them by storm. The Old Fort, defended by the Governor Colonel Cornelius O’Driscoll, falls after an assault is made possible by an accidental explosion in its gunpowder magazine, which kills forty. After some 200 are slain in the following assault, including Colonel O’Driscoll, the rest surrender, receiving quarter. Charles Fort, however, holds out for ten days and surrenders only after receiving guarantees that its 1,200-strong garrison can march away to Limerick. It is defended by the elderly and experienced Governor Sir Edward Scott, and his Deputy Governor Colonel Donal IV O’Donovan.