I haven’t gotten too far, but I did have quite a bit of trouble with 2-5, so I thought I’d pass along the technique that helped for me.
This is the mission where you are Haytham, dressed as a redcoat to infiltrate Southgate. First, “Find and Kill the General.” He is straight ahead along the right edge of the camp when you enter. He’ll be wandering around a soldier who is fixing the gallows with an American prisoner. You can’t free the prisoner, since you are there for the Mohawks, but use the crates and stealth to corner kill the general. He will have a red dot over his head once you get close enough so that you know you’re getting the right guy.
“Perform stealth assassinations from a corner spot- I had hidden blade active, walked up to a pile of crates until I stuck my shoulder against it, and waited for the officers to walk towards me. Apparently you can also use ‘whistle’ to convince someone to come to you, but it has the potential to also call more than you can handle. Hide, try again. I like to just get into the path of the guys I’m hunting so there is only one.
“Avoid firing line damage” This one took me forever. Turns out, as usual, I was doing it wrong! Once you get through the tutorial part, teaching you to hit A to use a human shield (keep reloading and doing it to get an achievement), simply charge ahead to the door of the fort, drop a smoke bomb to make all the dudes start choking, run through them, and scale the back of the building. When Silas comes to investigate, do an air assassination from the rooftop to finish the mission. I spent so long simply trying to make sure I wasn’t in a kill animation while they were lining up shots, but it seemed I was getting shot out of nowhere. Charging with a strategic smoke bomb has worked twice for me, both times I attempted it. Hope that helps!
Main Missions: Sequence 2: Infiltrating Southgate: Find and kill the general. Perform stealth assassinations from a corner spot. Avoid firing line damage. Find and kill Silas.