Blue Moon is one of the five main forces of Wars World. To date it has appeared in all installments except for Advance Wars: Days of Ruin/Dark Conflict (and the Japan-exclusive Game Boy Wars titles in which it is replaced with an army known as "White Moon").
Blue Moon specializes in a combination of overwhelming their foe with superior numbers and limiting the enemy's ability to counterattack by using weather conditions and indirect attacks.
Due to Clone Andy leading an invasion on their land, Blue Moon was at war with Orange Star at the beginning of the original Advance Wars, though later allied with them, co-finding the Allied Nations along with Green Earth and Yellow Comet to defend against the Black Hole invasion.
In Cosmo Land and Macro Land, where Advance Wars and Advance Wars 2: Black Hole Rising took place respectively, Blue Moon borders Orange Star to the north and in the former game, borders Green Earth to the south.
Blue Moon's Commanding Officers are:
- Olaf: the leader of Blue Moon, an ice cold CO. He specializes in the snow.
- Grit: a very calm and collective CO. He specializes in indirect combat units.
- Colin: he is an uptight CO who always tries his best to correctly carry out orders and give respect where it is due. He is also the younger brother of Sasha. His units are cheaper at the cost of their weaker firepower.
- Sasha: normally ladylike, but becomes daring when she gets angry. She is also the older sister of Colin. She gets more money for her properties and hinders her enemies' CO power.
- Blue Moon is modeled after the real world nation of Russia, as well as the Soviet Union. The irony of this is that in real life the Soviet army was known as the Red Army. While in the games, the opposing team is usually colored blue.