Just tried to do a no kill and no knockout playthrough but realised on the High Overseer mission that its not possible. It's a shame as it would have been a very challenging playthrough.
Unavoidable knockouts (this is for a pacifist playthrough, of course):
Spoiler
1) Overseer Jasper who guards Martin in the 2nd mission. Freeing Martin is a primary mission objective and you must free him to proceed — but it's impossible to interact with the lever that unlocks his shackles until you knock out the overseer. 2) High overseer Campbell. Non-lethal solution requires dragging his body to the interrogation room. 3) Sokolov. Knocking him out is a mission objective, so there is no real choice here. 4) Lady Boyle. You need to get her body to the boat in the basemant if you want to get rid of her non-lethally.
Unavoidable knockouts (this is for a pacifist playthrough, of course):
Spoiler
1) Overseer Jasper who guards Martin in the 2nd mission. Freeing Martin is a primary mission objective and you must free him to proceed — but it's impossible to interact with the lever that unlocks his shackles until you knock out the overseer. 2) High overseer Campbell. Non-lethal solution requires dragging his body to the interrogation room. 3) Sokolov. Knocking him out is a mission objective, so there is no real choice here. 4) Lady Boyle. You need to get her body to the boat in the basemant if you want to get rid of her non-lethally.
Yeah that's what I thought, thanks! Still only 4 knockouts isn't bad.