how to order units that will spawn in region to attack enemy

[emil23]

ok so im doing some siege map i want trigger in gui where a 10 units would spawn every 30 seconds in region x but after they spawn they will keep attacking and try to kill all units in castle. i know how to do this almost but idk how to order them to attack all units in castle

 

[Pyrogasm]

Tell them to attack move to the position of the castle. I would also periodically pick all the spawned units in the castle region and re-order the attack move. This ensures they can't get stuck doing nothing. Maybe... every 30-60 seconds would be frequent enough