The Siege of Old Wyk was a battle of the Greyjoy Rebellion. Following the destruction of the Iron Fleet at the Battle of Fair Isle, the royal fleet mounted a counterattack against the Iron Islands. While Great Wyk, the largest of the Iron Islands, fell to Stannis Baratheon, Ser Barristan Selmy of the Kingsguard subdued Old Wyk, paving the way for the complete defeat of the rebellion at the Siege of Pyke.
In the books
In the A Song of Ice and Fire novels, Ser Barristan Selmy led an assault of Old Wyk during the Greyjoy Rebellion.