I was talking with an elderly Metis man this summer who described the military tactics the Metis used during our annual buffalo hunts when dealing with expected attacks from the Sioux, our enemies at the time. His grandfather had been at the battle of graan kwatoo during a hunt in the early 1800's and described the inner guard, outer guard, reloading teams (of younger people and women mostly) and also something that interested me, the suicide squad.

The camp (of perhaps a thousand people or more) would circle, dig shallow entrenchments behind their carts, and then hold off the attackers. The suicide squad's job was to wait for the moment when the circling riders turned en masse and made a decided charge at one point, at which point the squad charged them directly and fought to the death as a way of slowing the charge as much as possible to give the entire defensive setup time to adjust to the point of attack.

This seems like fairly sound tactics, so I assume that it's been used before, and was curious: what are other examples of suicide teams/individuals being deliberately used in standard battle plans in the past?