"There's no apartheid in fox holes Colonel used to say".
I just now noticed, partway through writing the following, that your question is actually a month old! My apologies for the delay. For answers specifically -
"No apartheid in the front line" is indeed a saying; how true it was...depends, really. More can always be said if anyone would like to address themselves to the topic (or if you, OP, would like to repost it and get fresh eyes on it); for the meantime, we do have some previous answers relating to this matter by u/lofi_historian, formerly artificial_doctor.