Its ships used the prefix MSNS.
When the Manticore Colony was created following the arrival of the colony ship Jason, the development of the hyperdrive caused the local sector to become more populated and travelled quicker than the colonists had anticipated. Along with civilization came piracy and warfare. As a result, the System Navy was formed around several frigates and destroyers built in the Solarian League.
Less than twenty years later, the MSN had its first battle against scouting units of the Free Brotherhood, a wandering band of raiders, in the Megan System. One Manticoran frigate was destroyed, allowing the other to escape and return, rousing the rest of the colony to the danger.
In 1438 PD, the Fleet Marine Forces were created to provide boarding parties and shipboard security teams for the MSN's starships. Manticore proved to be much tougher than the Brotherhood's usual opponents, causing the raiders to continue on towards the Haven Sector.