|In 298 AC, Mummer's Ford
A Game of Thrones
Lord Lothar is assigned, along with others, the task of bringing Ser Gregor Clegane back to King's Landing to face justice for the crimes he committed in the Riverlands at the beginning of the War of the Five Kings.
A Storm of Swords
It is reported by Harwin that Lord Lothar was ridden down at the Battle at the Mummer's Ford and drowned. Harwin later accuses Sandor Clegane of killing Lord Lothar Mallery, though Sandor was in King's Landing at the time of the battle.