The Battle of Seagard was a battle of the Greyjoy Rebellion, taking place approximately nine years before the beginning of the Game of Thrones series. The forces of House Greyjoy, led by Rodrik Greyjoy, the firstborn son and heir of Balon Greyjoy, attacked Seagard, seat of House Mallister, on Ironman's Bay. The attack, however, was a failure and Rodrik Greyjoy was killed by Jason Mallister, the Lord of Seagard.
In the books
In the A Song of Ice and Fire novels, Lord Jason Mallister slew Rodrik beneath the walls of Seagard and drove his men back into the sea. It was the only time in three hundred years that the bell in the Booming Tower of Seagard was rung.