I keep seeing 1 comment and nothing is there. Normally when it's deleted is says so. Am I missing something?

I can not really give you a number, but there is a viewing guide for The Battle at the Somme from the Imperial War Museum (pdf), which may give some indication. (The movie on youtube) Interestingly, the most memorable scene was staged as were several of the larger explosions, while most of the footage behind the trenches is genuine.