Do you think that the white lotus took back Ba Sing Se without killing anyone with those 100-foot-tall walls of fire? No, you don’t expel an occupying force by just cutting the tips off of some spears. Avatar shows us the least-bloody parts of the recapture, but do not mistake Iroh’s depiction in a kids’ series for pacifism. Iroh is very clear, vocally, that violence is necessary in some cases. He teaches zuko to redirect lightning to send it back at the person who launched it, as he says “to use your opponent’s energy against them”. He prefers nonlethal methods, but that doesn’t mean he refuses to employ deadly force. He and his friends use fire against enemy metal tanks, which in reality would boil the soldiers alive. They use rocks to stop up the holes through which benders were actively shooting fire, which would rebound and fill the tank with that same conflagration. Those tanks get shot up hundreds of feet in the air and have hard landings on top of one another, which would not only concuss anyone inside to death, but would crush all of the tanks on the bottom. Iroh literally starts the liberation of Back Sing Se with a fire blast large enough to completely obliterate the titanic wall, as well as everyone behind it, in an instant. He doesn’t know how many soldiers lie behind that wall. He just destroys it, sight-unseen.