The Soldier is currently the weakest unit of the game, so they die easily if attacked by Tanks or enemy defenses. They are often used in massive hordes in attempt to overwhelm enemy defenses and breach their base. But when faced by Tanks, they are absolute bait. Soldiers are also the fastest unit in the game.

An alternative strategy for soldiers is to send them at the enemy defenses right in front of the Siege Tank so that they would soak up the turret fire and allow the tank to get to position mostly unharmed.

You can upgrade them by researching Power Armor at the Armory, which gives them more defense.

Adapted from

Commander CommanderSoldier SoldierTank TankSiege Tank Siege Tank