I think war may be less brutal (in some sense of the word) now than it used to be, but it depends where you are and who you get. I think it was seen as more normal. Cultural attitudes were probably more accepting of violence in general, and there were probably fewer legal safeguards and agreements in place to minimise mutual harm. Communication wasn't so good, so you could probably get away with more, and I know of one ancient book that shamelessly celebrates genocide, so in some cultures it wasn't even necessary to hide it.
So I guess it was very likely more accepted, but whether or not it was acceptable depends on what you mean by acceptable. I think it was often considered more acceptable at the time than it is now, at least in general, but to me in the here and now it wasn't acceptable, it was abhorrent, whatever the people at the time thought.