A player uses the recruit action to try and reclaim his two conquered pyramids. He places two troops of 5 units each into the pyramid spaces; one of the troops has a creature. Can he attack with the troop containing the creature, then recall his units after the battle and move the creature over to the other troop so it can participate in that battle as well?
No. All battles are simultaneous, so the creature could not take part in the second battle.