No. The battle objective needs to be completed and remain completed at the end of the round. If the unit is brought back (for example by the enemy skill Necromancy) and is back in play at the end of the round, the objective is not considered completed.
The same logic applies to the Conquer objective. If all units are defeated but then more are deployed (for example by the enemy skill Instigate), you need to defeat these newly deployed enemies in order to complete the Conquer objective.