unlike the movie, they were not really a welsh regiment yet - that came later.
there are some who say the two officers, bromhead and chard were fairly incompetent (bromhead was quite deaf and chard was just thick) and most of the defence was set up by one of the other officers & the sargent major.
i've seen adiscussion video on yootoobe that showed the cartridge boxes could easily be opened with a sharp blow from a rifle butt. they were designed that way.
lord chelmsford was even thicker, and blamed everybody but himself for the fiasco at islandwhana, his great friend victoria whitewashed him. the zulu king also warned his brother commanding the zulus at rorkes drift to never attack a dug in british position, which was ignored with the expected result, most of the zulu dead occurred at300-600 yards, the fierce hand to hand melee combat of the movie did not happen. the martini henry was just too much. it was the real hero.
islandhwana was played down and the great victory -really a minor skirmish at best - at rouke's drift got all the media attention and the medals to cover up chelmsford's negligence and stupidity.