The Earth-Mars Coalition, often called just the Coalition or the EMC is the coalition between the inner planets; the United Nations of Earth and the Martian Congressional Republic of Mars. Their military forces the United Nations Navy and Martian Congressional Republic Navy operate together as part of the Earth-Mars Coalition Navy.
Prior to the UN-MCR Cold War the Earth-Mars Coalition was formed, in order to police the solar system and prevent conflict between both powers. However as the Cold War began and progressed relations between the United Nations and Martian Congressional Republic soured, and tensions role. When the MCRN Donnager was destroyed and later UNN and MCRN forces on Ganymede engaged due to presumed engagement on the moons surface the Coalition was dissolved. It would remain this way until sometime after the Free Navy Conflict where both nations had fought together against the Free Navy.
Post-war the Earth-Mars Coalition was reformed, and ships from both fleets operated as part of the Coalition Navy. Although not considered a real threat the Coalition had to be prepared for any conflict with the Rogue MCRN faction.
When the Rogue MCRN faction reemerged at Medina Station now calling itself the Empire of Laconia the EMC fleet scrambled to prepare for an invasion of the Sol system. This came sooner than expected and when EMC and Transport Union forces were completely defeated by the Laconian battleship Heart of the Tempest the MCR and UN became client States of Laconia effectively dispanding the Earth-Mars Coalition.