Fort Conttroyor is covered in a perpetual storm, with tornadoes, so while it is a small island and you may think it is smart to circle it closely it can actually be very deadly. Stay at a distance and weaken the defenses with Mortar fire while you avoid the tornadoes and then get in close, no closer than 200m, to finish off the defenses with broadsides.
Once you are on the ground, enter the fort via the wall to the right of the main gate and then head south the engage in combat with the first Captain and his two Scout guards. This fight is unavoidable, so throw down a Smoke Bomb to kill him and then head back north. The guard to the east can be taken out with a Berserk Dart and the final guard to the north can be taken out with an air assassination.
After the fort is cleared you can get the Treasure x2, Animus Fragment x2, and start the Naval Contract, The Law of the Ocean.
