100 yards?

Yes, officially 351 dead, and at least 500 wounded, and no one was sure how many were wounded fatally.
A Sgt. Smith of B Company wrote his wife afterwards, and his estimate was nearer 800 Zulu dead in that action.

As the British troops were so heavily outnumbered you can bet your bottom dollar they started firing well in excess 100 yards!

Wikipedia? Since when was that the fount of all knowledge??????

It may help to put things in perspective. I do not claim to be an expert on 19th century infantry or cavalry tactics; however, I have read a lot about the firearms technology.

The Battle of Isandlwana took place in January of 1879. In terms of weaponry on the Anglo side it was similar to the Battle of the Little Big Horn Rive in America. The British were armed with the .577/450 Martini Henry drop block rifle. It was a black powder weapon (pre-nitro-cellulose) firing a bullet 450 thousandths of an inch in diameter with 85 grains of black powder propellant. The Seventh Cavalry Regiment used the 45-70 Sharp's carbine. It was also a black powder rifle using a drop block. I think that both of them fired a rim fire brass cartridge. In the case of the Sharp's carbine, it used only 55 grains of black powder propellant because it was a carbine with a shorter barrel.

I compare the Martini Henry to the Sharp's because by 1880 (and I do not know how many years before) army sharpshooters had used the Sharp's 45-70 (70 grains of propellant) to fire at targets at 1000 yards. However, this was never used as a battle field tactic.

A study undertaken by the United States Army in the 1950s, which I admit I cannot cite because I read only the secondary references and did not seek out in depth, revealed that since the Civil War through Korea more than eighty percent of rifle combat undertaken by United States troops were fought within 200 yards. Most of them, over sixty percent of the total took place within 100 yards. For over a hundred years they had been stressing the need to train for long distance shooting, but the opportunities to apply that training seldom occurred.

Isandlwana and the Battle of the Little Big Horn are all excellent examples of the advantage of numbers, in the case of the latter the advantage included the advantage of firing rate, over long-range accuracy. At Isandlwana the native Zulu warriors were able to use terrain (describe in an earlier post), numbers, and poor logistics of the British soldiers to negate the long range advantage of the Martini Henry over the Zulu spear. In the case of the latter, the combined Lakota tribal warriors were able to use the rapid fire Winchester Model '73 combined with their advantage in numbers to overcome the range capability of the Sharp's trap door carbine.

The original posting and question was actually about waiting until the opponents closed within 100 yards. I think like one responder mentioned that it is more likely that they would open fire at 400 to 500 yards. However, the land around Rourke's Drift was rolling hills and I recall one description of the battlefield saying that attackers could close within 200 yards while remaining in defilade. It is not unreasonable for the senior NCOs to order volley fire at 100 yards in order to keep their soldiers under tight control.

On the other hand, they were fighting from fortifications and they had ample ammunition. Those conditions encourage the use of free fire or 'fire at will' (poor will, God bless the lad) conditions.

Oh well, Hollywood (neither Pinewood) has ever allowed the facts to get in the way of a good story.

The best diplomat I know is a fully charged phaser bank.