The siege of Carrigafoyle Castle took place on Easter in 1580 near modern-day Ballylongford, County Kerry, Ireland, on the southern bank of the Shannon estuary.

Carrigafoyle Castle – built by Conor Liath O'Connor-Kerry in the 1490s and considered one of the strongest of Irish fortresses – was a large tower house, of the type particularly common across the north of the province of Munster.

The castle was known as the guardian of the Shannon because of its strategic command of the shipping lanes that supplied the trading city of Limerick, some 20 miles (32 km) upriver.

During the rebellion the castle was held by 50 Irish, along with 16 Spanish soldiers who had landed at Smerwick harbour the previous year in the 1579 Papal invasion;[1] there were also women and children present.

The final assault, led by Captains Humfrey Mackworth and John Zouche, was concentrated on the part of the tower furthest from the cannon, where the defenders were holding out.

The survivors fled through the shallow waters, but most were shot or put to the sword; the rest (including one woman) were brought back to camp and hanged from trees.

The castle at Askeaton was abandoned before the guns (its Spanish defenders blowing up the walls), and the garrisons at Newcastle West, Balliloghan, Rathkeale, and Ballyduff slipped away soon after.