Assume a player character has 5 levels in Paladin and 5 levels in fighter (Battle Master).
The character casts find steed and summons a war horse and mounts it. During their turn in combat, the character attacks once, then uses their Commander's Strike maneuver and chooses their war horse.
Would the Commander's Strike maneuver allow the war horse to use its reaction to make an attack?
If so, would the warhorse also be able to use its Trampling Charge trait after its attack (assuming that it moved 20 feet in a straight line)?