A Clash of Kings
The master of the White Hart plans to slip anchor from King's Landing and go over to Stannis Baratheon, but his plan is uncovered by Lord Varys. Tyrion Lannister orders for him to be put to trial by King Joffrey to send a message to the other captains.
The White Hart is a part of King Joffrey I Baratheon's fleet at the Battle of the Blackwater. During the battle, the White Hart is successfully boarded by the Black Betha. After the Swordfish rams a hulk filled with wildfire, the White Hart is engulfed by wildfire and destroyed.