Those were members of Penal Battalions - you screw up: show cowardice, political non-compliance, etc. and you were sent to them. They went in first to set off the anti-personnel mines and other no-chance operations. Those that survived one battle were sent back to the "relative safety" of front-line infantry.
In the '80s I worked with some anti-Khomeini Iranians who had a bootleg tape about the Iraq-Iran war. It showed Australian doctors trying to fix hundreds of children blinded in the war.
Khomeini sent them, with their parents' blessings, to fight the Iraquis. They went in ahead of the infantry, waving their little green books of Khomeini's sayings, tripping the ping mines as they went along. The ping mines were set to explode waist high on a man, so the kids, being shorter, caught the blast in their upper bodies, hence all the blindness.
After VE Day, Eisenhower was showing off flail tanks to General Zhukov, who remarked that he just marched infantry to clear mine fields.
I recall my world history teacher saying that the Soviets would only have 1 gun for every 5(?) troops that were sent into battle. The others would drop their clubs and pitch forks when one with a rifle was shot.
I have no idea if it was true or not, but sounds about right.
And while the Germans had their jet fighters towards the end of the war, they were so limited on fuel that they would use mules to taxi the fighters out to the runway.