The fall of Athlone occurs on June 30, 1691 during the Williamite War in Ireland. Despite the bravery of legendary Sergeant Custume and others, severely outnumbered, the Connacht side of the town falls. The remainder of the Irish garrison retreats to Limerick.

The first assault on Athlone comes in 1690 after the defeat of the Irish at the Battle of the Boyne. General Douglas, leading a substantial force of possibly ten thousand consisting mostly of Ulster regiments, is the Williamite commander. When he arrives at Athlone he is confident that he will quickly conquer the town for King William III. However, he had not reckoned on the spirited defence of Athlone by Colonel Richard Grace. Grace, who is at that time over seventy years of age and a veteran of the Irish Confederate Wars and Governor of Athlone, refuses to surrender. After a week the Williamite army retreats.

In 1691, determined to capture Athlone, the Williamites return with their full army of almost 25,000 men. The army is under the command of a Dutch general, Goderd de Ginkell. The Jacobite forces are under the command of a French general, the Marquis de St. Ruth. The Williamites breach the town wall and capture the Leinster town. The Jacobites, in a desperate attempt to keep the enemy at bay, break down several arches of the bridge and the Williamites quickly attempt to repair them. Sergeant Custume leads his men onto the bridge to dislodge the Williamite repair work. They succeed in doing so before meeting their death at the hands of enemy fire.

Ironically the capture of Athlone comes when the Williamites discover the ford that gave Athlone its name and in a surprise attack dislodge the Jacobites and take the castle by storm resulting in wholesale carnage and slaughter. For his services to King William III, but certainly not to Athlone, Ginkle is given the title Earl of Athlone. The bravery of Sergeant Custume has not been forgotten as the military barracks in Athlone is called Custume Barracks in his honour, the only barracks in Ireland named after a non-commissioned officer. A street adjoining the town bridge is named Custume Place.