A U.S. film that is highly implausible in almost every respect. A young woman disguises herself as a man and follows her fiancéé into the trenches during World War I to find out what war is really like.
After 30 mins, an attack by Mk VIIIs succeeds, despite opposition from Germans using drums of a flammable substance.
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Did any army used the barrels like that, rolling them down burning (question if metal barrels exsisted is answered somewhere else on this forum and answer was yes)?
Where there "fighting" women in Western armies, I don't talk about YMCA, medical,... soldiers. I've seen a picture of a women who was serving in Russian Army (not sure of nationality) in WW1
First question is an interesting one. I don't know the answer but whole generations of Hollywood special effects men have shown such things. Anyone who have ever rolled 44 (imp) gallon/ 200 litre drums knows the ruddy things never go where you want them - which may or may not have some bearing.
On the second question, I think there were just an isolated few on the Allied side who smuggled themselves into the ranks. You will find some scattered instances in the two specific topics:
You'd have to be lucky enough to find somewhere where the terrain was conducive to rolling barrels down hills, plus of course the area would have to be free of barbed wire, shell holes and other obstacles, so I think pretty much impossible and into the realms of Hollywood History