As I said elsewhere - and and all references to God were curiously missing from the movie. Even the opening card talks about the soldiers hoping for a miracle - not praying for a miracle - hoping for one.)
Nolan didn’t want to make a movie about miracles or God but some odd humanitarian statement which doesn’t come through and, apparently, he ignored historical fact that was more interesting to tell a story that wasn’t because it didn’t jive with the story he wanted to tell.
Throw in a huge mix of PTSD, that has to be in every war movie now.