"Use a fire barrel to sink a ship" is an optional mission objective in Sequence 7 / Memory 04: The Fireship
Walkthrough[edit]
As the battle rages, let a damaged Schooner or gunboat get behind you. As it moves in to attack you, loose a set of Fire Barrels on it. Weaken Schooners with Cannon fire if needed and then sweep the Jackdaw's stern by them to drop the barrels on them.
