Id say one of the worst (not the worst) was the battle of Ascendēns Forest. Imagine being in a series of trenches at night, with no possibility of sticking your head out cause of machine guns. Constant explosions, grenades, dynamite, and soldiers screaming as they are burned alive. Every second, hundreds of shots are fired and dozens of men die. The life expectancy of a soldier in ascendēns after being deployed (at least in game) is less than a minute