Above is a fair description. In addition:
Right click on your clipboard, then click Country Status. It will show you how many are logged on for each country, how many are in flight, current ENY restrictions for each country and your countries status relative to winning the war.
ENY is based on total number logged on, not those in flight. This keeps big squads for instance, from sitting in the tower to remove ENY then all upping at once and unbalancing the arena.