James Joseph Emerald said:
Why is the majority of people posting to this thread acting like they know what they're talking about? Unless you're posting this from a jail cell, I doubt anyone actually does.
The military don't even go into this stuff that much anymore. Fighting with knives/bayonets is so last century. Hell, nowadays soldiers don't even kill people with guns, believe it or not. It's all about holding position until you can get in artillery or a gunship to blow up whoever's shooting at you. They say in Iraq, for every 250,000 rounds fired, only one combatant is actually killed by small arms fire.
Ha ha a slightly better ratio than the one assessed for WWI... I'm no soldier, never been in a war, but have had a few moments with guns (shotguns and a rifle once) which were kinda hairy and been in enough fights in my youth to know a few things:-
Movies lie. Guys don't go limp with a single punch, knocking someone out with a straight punch to the head is pretty darned hard and certainly not guaranteed. I've done it a couple of times but each time it's been more luck than anything.
The silent kill is a myth. Death is ugly and loud in almost every form. Whether it's the gurgles of a throat cut (from the cut in the throat not the mouth itself, so clamping the mouth would be ultimately pointless), the sound made from a silencer (which is never truly silent), to the sleeper hold which still allows for grunting, gurgling and thrashing all of which make noise.
The neck break... Dear god every guy I know thinks this is the best silent kill ever and it's total Hollywood BS. As soon as you put your hand on someone's face their instinct is to pull away, meaning you not only have to break the bone but also the force the strong neck muscles pulling the other way. I've heard of techniques that counter this, but they take skill, practice and not a small amount of luck.
If you had a non-proficient combatant who panicked while attacked you MIGHT be able to get off a pretty quiet kill, but any soldier worth their salt, when attacked, would do considerably more than thrash about and go limp.
With regards to the OP, really you're down to poison or gas. If in a sealed room CO would be great because it starves the body of oxygen slowly and puts the person to sleep. The same would be true of a sedative, but it would need to be a contact sedative or the person targetted would feel the pinprick of a dart or needle. A contact paralytic would similarly be good, something on a coin dropped near their sight (if on a grassy plain) would work, or a note if somewhere more audible as long as there is a slight breeze and you're upwind. Still, not very easy to target an individual and not foolproof, depending on individual resistances to the paralytic and time taken for full effect.
Oh, I just remembered, there's the British Army guy who killed someone from several kilometres away. While silenced and in mountains the noise was supposed to be dispersed enough that the guy got hit without ever seeing a muzzle flash or hearing the sound of the shot. Got two guys that way, although under exceptional weather conditions and using tremendous skill. I doubt anyone reading or contributing to this would manage the same shot!