It is not endless retaliation attacks. The limit is the targets AP, since it costs AP to move around. So usually you get 3-4 hits depending on terrain on the enemy. And same goes for your fleeing mercenaries. And as many times, again I do agree with GoD. You mentioned footwork, well you have the rotation skill aswell. Using these two skills tacticaly should help you a lot with wavering brothers. Fleeing is a panic move, fear for life, even in real life you will see people running around in extreme conditions like headless chickens, and here you are fighting spawns of evil. And surrounding gives bonuses not only tactical but debuffing aswell.
Beside footwork and rotation there are different weapons that can help you with saving brothers. Shieldbash(shield) Repel(2h pike pitchfork) Hook(billhook) Stun(maces 2hsword crits). The taunt skill should be useful aswell tho imo is not yet good enought, the enemy still targets the weaker armored units. Again check the defensive tree tier 3 skills, ofc shieldwall, riposte weapon skills aswell. You do need to find the balance between offense and defense to maximize your groups potential just as much as tactical placement or weapons of choise.