This is a fort infiltration mission with three parts.
The first part is sailing to the fort. You will be given the same 'Lexington' Stripped Brig that you captured in the last mission. No combat here. Click on the fort to enter it.
The second part is the infiltration. Walk in, interact with the paper, and go inside the fort. There will be three piles of explosives you need to interact with, but the guards will stop you from doing so. Go to the top of the fort and fire the cannon.
This will start a chain reaction where the first guard will run up to check the cannon. Plant the fuse on the explosive, then wait for the next guard to try and put out that explosion, which will allow you to go to the next explosive pile and set it alight. The captain will check the second pile and you can set her pile on fire too.
A timer will start. Run out of the fort - you'll have just enough time. You will fight a 3 pack of Mithradati on the way out. Click on the grappling hook to return to your loaner ship.
The third part is a simple sailing escape instance. Reach the x on the map to finish the mission. Use your sail repair class skill - the enemies fire sail damaging shot.
Infiltrate the Fort Distract the Guards Plant the Explosives (0/3)
Escape the Fort (8s)
Escape to the Open Sea