The Royal Orbital Marine Corps was founded in the year 4200 when it was realised that the space capability of mankind was close at hand and that the newly established space missions would undoubtedly require some form of military that specialised and were operational in tasks affected by the lower gravity fields.
The original leader was former astronaut and NASA director, Admiral Neomi Diseth an Asian female who, with the help of military leaders across the planet to pull together an organisation that would aid in planetary and interplanetary missions.
After its establishment it grew from there like a normal military faction and somewhat took over and replaced existing military, recruiting fresh troops into the corps as well as retraining former soldiers as Orbital Troopers. All Navy members were given detailed classes and retrained as being able to look after and commandeer space vessels with ease.
The retraining and decommissioning of surface fleets and armies was relatively easy as the prospect of space no longer being a limitation excited the entire world and thus turned their attention away from fighting one another and to get out and explore the galaxy.
The first fully trained and prepared crew for space exploration and combat was the crew of the Primus Kessinger a corvette that orbited the Earth and then the moon before remaining in Earth's orbit for the duration of its time withing the fleet. Primus Kessinger allowed for the dismantling of all space stations as the corvette allowed it to return to the planet's surface for a change of crew and refueling and any required repairs as well as restocking of supplies.
When mankind became fully space operational in the year 4432 they had amassed a small fleet that included four corvettes and a cruiser that acted as a the fleets command ship. During this time both battleships and the Particle Drive were being made prototypes and drafted for use in the near future.
When the Particle Drive was finally constructed it was placed aboard the cruiser Particle Nocte which made its first successful jump the following month after the particle drive was linked to the onboard computers which were refitted with a new data chip that contained a map of the solar system and a number of other systems which allowed for easy jumping if coordinates were correctly inputted.