This is one of the final main quests, where your objective is to eliminate the key member of the Templar Order. You can start it after completing the "...Everything is Permitted" quest. To do so, head to the Assassin Bureau in Kingston. Assassin Antó will tell you where to find your target and how to get close to him.
Edward pursues his first of three primary targets: Governor Woodes Rogers.
You'll find the diplomat north of the church with the viewpoint. Once you get close to him, he and his two companions will head west down the street, so be careful as you don't want him to spot you.
Tail the drunk diplomat and his companions. You can climb along the rooftops or simply stay at a safe distance behind them. After a moment, the diplomat will step into a side alley to relieve himself.
Follow him - you can safely walk right past his companions, who will stay on the main street.
The diplomat will turn into one of the yards to relieve himself under a tree - take advantage of this, sneak up on him, and assassinate him.
Loot the diplomat's body. Edward will automatically put on the Foreign Diplomat Disguise.
Hint:
Enter the estate grounds through the main entrance. The guards won't recognize you and will let you through without any trouble, mistaking you for an Italian diplomat.
Enter the central courtyard, where Woodes Rogers' speech will begin. Don't get too close to him, though - he'll recognize you and you'll be shot. Besides, you don't have any weapons on you other than your blade, as you left them at the Assassin Bureau at the start of this quest.
Hints:
Look to the left - there is a bench by the wall. Approach it and sit down to blend into the crowd.
Wait patiently until Rogers finishes his speech and begins moving around the estate grounds. As he passes by you, you can take him out unexpectedly. A cutscene will automatically trigger.
Once the cutscene ends, you must leave the estate grounds as quickly as possible and escape the guards who will start hunting you down. You can try running out through the main entrance - and you should make it, even though there are a few soldiers there. Alternatively, you can run along the building next to the bench you were sitting on just a moment ago, and jump over the wall onto the street.
Once you break line of sight and lose the pursuit, return to the Assassin Bureau to finish the quest. Your next target will be Bartholomew Roberts, who is hiding in Africa. Another main quest - Royal Misfortune - will be unlocked.
