I saw it when shown on TV back in the mid 1960s. Not long after, 1968, a book came out about a critic’s review of all the movies on TV. I believe it was by Rex Reed.
So I checked out what was said about ZULU.
Talk about an agonizing screed! Basically he weeped and wailed about how such a movie could be shown on TV in those bad times of the 1967-1968 race riots!
Got it on DVD! Great movie! and the later movie ZULU DAWN also is a great movie!
For more info on the battle read THE WASHING OF THE SPEARS by Donald R. Morris.
I met Donald Morris at a book-signing 25+ years ago and he signed my copy of his book. He used to be a newspaper columnist here for the Houston Post when they had a slate of good conservative writers before they went over to the dark side. He said he liked the movie Zulu which he felt was "true to the spirit of the event". He had not seen Zulu Dawn.
Another good book on the 1879 Zulu War with info that was not in Morris' book is Like Lions They Fought by Robert Edgerton.