Which Weapon Caused the Biggest Casualties in the War?

I wonder what the casualty rate of Russian penal troops were when they sent them over open ground laced with mines and against withering fire with allmost no weapons.

 

Hi; I believe it was Soviet Marshal Zhukov who once said " it takes a brave man to be a coward in the Russian army "

 

I wonder if the film enemy at the gates was true, the part at the start were they rushed man of the boats, give them one rifle between about four and a few bullits and sent them into hell.