Assassin's Creed 4 Black Flag Walkthrough Part 51 – Sequence 8 “Vainglorious Bastards”

Optional Objectives:
Use the fort's defenses to sink a ship
Damage the Royal African Pearl with an Upgraded Ram

Head for Charles Vane's Ship at the starting point of this memory. Be absolutely sure that you have upgraded the Ram on the Jackdaw at least once. This will allow you complete the Optional Objective. If you have Pinos Isle, this is a great Fast Travel point as you are only a short distance from the start of this memory (even if you have to fight out of it). Otherwise, go for whatever you can and sail to it.

With the start start of the memory you will be hunting down the Royal African Company. Stay behind the Princess, Vane's ship, until you reach the Green Search Zone. Once inside the Search Zone keep in the wave of the Ranger. This will ensure that you are not detected by other ships. When the Ranger slows, look to the right with the Spyglass to find the Royal African Pearl. You can spot it as the Ranger is going around a large Rocky Island. To the right of it you will find your target. Time to take it down and board it.

Start by charging the ship as fast as you can. For now all you can do is loose the swivel cannons and the occasional round of Mortar fire on it. Just chase it as best you can with what artillery is available. The Ranger will be loosing its artillery, doing have damage.

When the Ranger gets heavily damage, you need to get in close to it very quickly. This will trigger a cutscene with the crew quickly climbing over to the Jackdaw. When that is complete then the next part of the memory will trigger with the optional objectives.

The first Optional Objective is easy enough. Charge at the Pearl with little concern for anything else. Ram her then focus on taking her down to her final slivers of health. Break away from the Pearl when it has been disabled. There are some ships in the area, destroy all but one of them. This final one you want to damage heavily then run toward the fort. If it is close onto the Jackdaw, it will take little from the Fort to take it down. This can take several attempts.

When things are done, you need to board the ship. There are a number of objectives possible. If you need to take out powder reserves then you need to start immediately on that with the Swivel. If you do it during your boarding there is a good chance of losing crewmen to the blasts. After all that you will get a cinematic to end out the memory.