I said
This is a frontal assault which doesn't mean he physically runs behind the spearmen only diagonally beyond where their spear points are effectively pointing at him.
He can then attack with relative impunity while they try to sort themselves out and get their weapons back into an effective position - ie retreat, shorten their grip on the spears or draw a close quarters weapon.
As I am ignorant of these matters wouldn't either side have some safegaurds setup to prevent such a maneuver like Archers, Slings or some other distance weaponary.