cannon fodder 
noun [mass noun]
Soldiers regarded merely as material to be expended in war: they ended up serving as cannon fodder in Vietnam...
- Wars are lost when the leadership regards its soldiers as cannon fodder.
- Brainwashed by the Nazis, conscripted and sent to fight a war that he at first eagerly embraced, Metelmann was the universal soldier - both cannon fodder and killer.
- Also, the Russian commanders had no wish to be used as cannon fodder and tried to discuss ways in which all anti-communist forces might unite against Stalin.