I am not an expert but try this. Create two trigger zones, (1. Message to Tanks, 2. End Mission.)
Now you need two triggers.
1. Type= 1 once, no event. Condition= Part of Group in Zone, name group, name trigger(Message to Tanks). Action= "message to Group", name Group, Type your message in the box, set how many seconds you wish for the message to appear.
2. Type= 1 once, no event. Condition= (either) All or Part of Group in Zone, name group, name trigger(Mission End). Action= "End Mission", Pick winner, type message.
Hope this helps you.:thumbup: