EarthForce is the military branch of the Earth Alliance, Earth's governing body in the fictional Babylon 5 universe.
Earthforce was founded as a peacekeeping militia with the majority of its members deployed to control terrorist aggression on the ground. It was initially formed from contingents provided by Earth Alliance member countries and later transitioned to direct individual recruitment.
The Fleet was not formed until after the Earth Alliance purchased Jump technology from the Centauri. The first major action of Earth Force was the war against the Dilgar which ended in victory. Unfortunately, this made the force overconfident and they decided to approach the Minbari despite warnings that doing so would be dangerous. As it happens, the warnings were correct as an inadvertently premature first contact ended violently due to a serious misunderstanding that provoked the Earth-Minbari War in which EarthForce found itself hopelessly outmatched. The war culminated in the climatic Battle of the Line, in which the bulk of EarthForce's remaining forces were annihilated before the Minbari mysteriously surrendered on the brink of absolute victory (or not so mysteriously as it later turned out).
EarthForce, as part of EarthGov, is headquartered in EarthDome (Geneva, Switzerland) with the President of the Earth Alliance as Commander-in-Chief with the Joint Chiefs of Staff responsible for the day-to-day operations with final authority reserved for the Earth Alliance President. All EarthForce officers and crew train at EarthForce Academy. (The Psi Corps was also founded as part of EarthForce.)
Divisions:
EarthForce is organized into three separate branches:
There is also an Internal Affairs division of EarthForce, which can draw personnel from any one of the three divisional branches. ("Eyes") Officers and crew are allowed to transfer between branches; Richard Franklin (father of Dr. Stephen Franklin) once served as first officer on the EAS Ares, but by the time we actually meet him, the elder Franklin was a general in the EarthForce Marines. ("GROPOS")