The Surgeon Early Death
In the memory The Surgeon, you are first introduced to the target Silas in a scene. While playing through I discovered a way to assassinate Charles Lee. Position him so that he's around a corner. Then whistle for a guard. When the guard gets close enough on the other side of him, the weapon icon will light up to show you can do a corner assassination.
Be sure to use a smoke bomb so you won't get seen otherwise you'll fail the mission. I tried this on Charles earlier in the memory with no luck. Even if I had been successful, the game would have desynched me for an ally dying. I guess the game developers weren't worried about Charles dying in this part of the memory.
Blitz
The fastest way I could kill Silas. Right after the obligatory human shield tutorial, run straight to the fortress. There will be a brief lag when you get close from the game loading NPCs. climb up at the place shown and shoot Silas. Luckily I didn't have to move the camera since he's right in front of you, although you may target another enemy next to him or if enemies are passing close by (the chances of which I'm not sure of).
http://youtu.be/OzVmrAIpxD4
[Front-paged. -stabguy]
Charles Lee and Thomas Hickey Double Deaths
In the memory Johnson's Errand, you accompany Charles Lee and Thomas Hickey in returning an item for William Johnson. After the cutscene your allies distract a group of posted guards (pretending to be drunk?). There's a place just outside of a memory wall where you can drown them. They reappear for a scene after you kill the guards in the area. After that you can drown them again. They will, of course, reappear for that scene as well, but after that the game records their health. Another thing to note: After the scene where Haytham lets the leader of the enemy group go you can kill him, although the game counts it as killing a civilian.
Edward Braddock, John Pitcairn and Charles Lee deaths
Here's an opportunity to kill Edward Braddock in The Soldier memory. When you are tailing him you can assassinate him just as the scene is starting. Wait on a nearby roof. Then at the right time air assassinate. The timing has to be pretty precise. Any earlier and you desynch; any later and the air assassination fails (as indicated by the lack of sound effects from the kill). In case anyone doubts this as a kill, the assassination stats have it recorded.
Now for John Pitcairn and Charles Lee (it may also be possible to air assassinate Pitcairn before the scene when tailing Braddock, but I was just aiming to kill Braddock for that). After the fight, Pitcairn and Lee just stand there, waiting for the next scene which starts when you get close enough to Braddock. So just move them to the closest place to drown them.
http://www.youtube.com/watch?v=TS8teuCiNvY
[Front-paged. -stabguy]
Early Deaths
After reaching southgate, your five Templar allies each go to a predetermined spot. Once they reach it, they stay there until the next part of the memory. Moving them isn't any trouble since they don't bother to move after that. So I move them all to the docks. The idea was to kill them all in one swift move using a horse. However I didn't move them close enough to the edge for fear of accidentally pushing them off the edge.
Conversations with the Templars
Haytham's Templar allies each blend in with some guards before the fight. While blending they have a conversation with the guards. Their entire conversations were put in the video to keep it short.
Thomas Hickey: Has a conversation with a group by the docks.
Benjamin Church: Has a conversation with a group by the general you have the option of killing.
William Johnson: Has a conversation with a group near the outer part of the camp.
Charles Lee: Has a conversation with a group near the middle of the camp.
John Pitcairn: Has a brief conversation with two guards by the outhouse. I didn't include his conversation because of some problems I was having, but you can hear him in the background of another one of the conversations, "stop slouching, soldier".