I saw an interesting "Secrets of the Dead" episode where they postulated that the reason the British were over run by Zulu warriors is because their rifles created a smoke screen. I can't remember the name of that famous rifle, but it did use a heavy charge, and it predated smokeless powder.
They were able to disprove the theory of the lack of ammo because of the number of smashed open ammo boxes lying around at the scene. They even went pretty in depth into the zulu warrior culture and zulu shamanism during the period. It was some good TV.
While we're on the subject. A story of a historical situation of a good infantry, actually they were cav scouts, leader who overcame overwhelming odds by applying fundemental infantry tactics is the account of the battle of Beecher's Island. Do a search on it. There are some good articles if you can find them.