Assassin's Creed IV: Freedom Cry Walkthrough Part 3 – “A Ship Of His Own”

Optional Objectives:
Use Bastienne's girls to distract the guards
Distract 4 guards with Firecrackers

Head to the marker on top of the building. There you will find Augustin waiting for Adewale. He will point out a ship in the harbor that Adewale can use. This gives you the firecrackers. These can be used to distract guards and lure them away from areas.  Follow the tutorial on Firecrackers and, if you want, kill the guards that come to investigate them. From there make your way down to the beach. Use this time to drop Firecrackers where you see Overseers. This will lure them over to that location. From there just pounce on them with Aerial Assassinations to get a total of 4 of them. That will satisfy the first optional objective.

As you approach it you will see a number of Bastienne's girls that can be hired for free. Get to the girls. After that you need to approach either of the marked gunpowder barrels. Send the girls ahead when you are close to distract the men. Grab the Gunpowder only after you tag the Gunner on the watchtower with a Sleep Dart. Now carry the keg over to the tower and ignite it. Duck into a Stalking Zone to the South. Wait for the keg to explode.

Now you just need to make it out to the ship and up to the top mast. First though, head out into the water from the Stalking Zone. Now make your way, using stealth swim, out to the ship. Go to the far side of the ship and climb up it. Now shimmy your way over to the right and up the stern of it. Wait for the Captain to walk by then kill him. Now head for the stern mast and climb up. Once on the first landing, kill the nearby Gunner and hit the second with a Sleep Dart. Continue your climb from there up to the top of the mast. Once Adewale makes it to the flag the memory will come to an end automatically.

To move onto the next mission you need to liberate 150 Slaves. The best thing to do is head for the Slave Ship that is marked ahead of you. There are a lot of slaves on board it that you can free. Take out its escorts with Mortar fire, Heavy Shot and Chain Shot. Slave ships do not need to be damaged to be boarded, you just need to take out their escort. Board the ship after that to free the slaves and boost your numbers.