Assassin's Creed 3 – Naval Mission: French Involvement

Optional Objectives:
Limit Damage to La Belladonna to 50%
Sink more Enemies than La Belladonna
Kill the Officer within 60 seconds

After the opening cutscene sail to the starboard (right) of the ship you are escorting. It is easiest to get there by instantly going to Full Sail and holding that speed.

The first optional objective is one of the easier ones as you need to simply keep yourself between the La Belladonna and the gunboats. Immediately drop to half sail to take advantage of the Aquila's manueverability. If you have the Grapeshot upgrade there will be little contest if you can line up the proper shots. Mix that in with good maneuvering and you should easily be able to sink more than the 11 the La Belladonna sinks.

With all that done then it is time to face down a Man-O-War. It will appear and disable the La Belladonna. Immediately change to chain shot and move in for a shot on the Man-O-War. After that it is time to deal with the third optional objective. Ram the Man-O-War to move onto it properly. The Officer is marked with the usual Red Target. Run over to the right once on the Man-O-War, going around the flames and giving chase to the Officer. If Connor gets caught by some of the crew men do not worry, focus on getting a Counter-Kill following by a kill streak to just tear through anyone who honestly gets in the way. After the first set of men, if the Officer is still alive, cross the deck and head to the edge of the boat. Head up to the bow of the ship where the Officer will finally stand and fight. If possible, get a Counter-Kill on one of the men then move the kill streak onto the Officer for a quick finish. If this is not possible, break his defense twice and he will be on the ground, set for an easy kill.