In most Inner Sphere and Periphery militaries, soldiers with the rank of Captain command companies. In the various naval forces, the rank (position) of Captain is usually a ship's commanding officer and is roughly equivalent to a Colonel of ground forces.
In the first Star League, a Captain commanded a company of ground forces. In the SLDF Navy, they commanded DropShips. In any case, these officers were expected to demonstrate initiative.
In the second Star League a Captain is the front line commander of a company of ground troops. Unlike their first Star League counterparts, SLDF Navy officers at this rank are called Commander and command a flight of AeroSpace Fighters, a DropShip, or act as the Executive Officer of a JumpShip or WarShip.
In both cases, the rank insignia for an SLDF Captain is two green bars.
The LCAF and LAAF use the rank of Hauptmann for company commanders. These officers are the highest rank that routinely see combat. To honor these officers, the Lyran Alliance's first OmniMech was named the Hauptmann.
The DCMS uses Tai-i to indicate company commanders. Their symbol is a royal blue "5". The Draconis Combine Admiralty rank is Chu-i. A chu-i in the DCA frequently commands a flight of six AeroSpace Fighters.
Prior to Sun-Tzu Liao's ascension to the Celestial Throne, the CCAF used the rank of Commander to indicate the commanding officer of a 'Mech lance or aerospace squadron, or the commanding officer of an infantry or armor company. They could also sever on regimental command staffs or mid-level managers in non-combat duties. After Sun-Tzu introduced the Xin Sheng reforms, the rank was retitled to Sang-Wei or Captain.
A Pai-Zhang is the equivalent rank to Captain within the Warrior Houses, although it denotes the leader of a 'Mech lance or infantry platoon, or if senior enough a member of the command staff.
The CCAF Admiralty rank uses the same insignia, but is named Kong-sang-wei.
Like their counterparts in other Successor States, FWLM Captains are company commanders. They use two thick gold bars on a purple background as their rank insignia. In the FWLM Navy, an officer at this level is known as a Lieutenant Commander and commands a ship's watch or heads up a department aboard ship.
Star Captain is the rank used by the Clans for the commanding officer of a Binary or Trinary. Commanders of DropShips and JumpShips are also given the rank of Star Captain. Clan Hell's Horses also uses the rank of Nova Captain, who commands a Supernova.
In the KungsArmé officers with this rank are called Kapten, Swedish for Captain. These soldiers wear a green patch with a vertical silver bar crossed at the base by a small silver bar as their rank insignia.
In the Magistracy Armed Forces, purchasing a company command means the officer holds the rank of Commander at a cost of between 16,000 to 35,000 C-Bills. They also used to be able to command battalions until the reforms brought about in the late 31st century. This rank is also used by the Magistracy Navy, where Commanders serve as department heads. Commanders wear two gold edged blue-green diamonds set inside each other to show their rank.
In the TDF, a Subaltern (not be confused with the AFFS rank) commands a battalion of conventional forces or a 'Mech company, or is a department head among the support branches. Among the aerospace branches the rank is known as Air Master, Junior Grade or Air Master, JG and either serves as a department head on a navy vessel or assistant commander of an air division. In either case, their rank insignia is a single gold ring filled with a red dot.
With the interest the Legiones Marianes have in recreating the Roman Empire, company commanders are known as Principes, a Latin word meaning leader or ruler. (To avoid annoying the Imperator and Caesar, the latter translation isn't used.) A principes wears the silver triangle of a legionnaire with an inset black triangle to show their rank.