From my reading of Candian/Rhineland campaings, it actually happened quite often,Especially in wooded/urban area(it seems) but usually, when people were getting overun, a few were dying/wounding and the winning part would soon have prisonners. But compare to Arty,small arm fire casualities, I need to say that it's not really comparable, that is true.
But my point was more that it's not something that could be neglected compare to a more recent scenario Especially when assaulting buildings/forest
It may be something about british tactics also... like creeping barrage and overrun the position after?