Mars Defense Perimeter
The Mars Defense Perimeter was a Starfleet planetary defense mechanism, designed to protect the inner planets of the Sol system, and specifically Earth, from intruding hostile starships. Part of the defense perimeter was a series of attack ships as well as static heavy weapons platforms.
In early 2367, an attacking Borg cube crossed the perimeter and was able to easily break through the defensive lines, destroying the ships sent to intercept it within a matter of seconds. (TNG|The Best of Both Worlds, Part II)
In 2368 a Mars Defense Perimeter ship was stored in the ship graveyard of Surplus Depot Z15. (TNG|Unification I).
In the star Trek freedom universe, the Mars Defense Perimeter was reinforced by Admiral Rodrigo Doenitz, after he seized the federation Government on Earth. Later in Late 2407 elements of the 52nd fleet assaulted the Mars Perimeter, focusing on knocking out the system by taking control of the central most command center located on Starbase Valhalla.
The USS Boudicca supported by several other key vessels in the 52nd Fleet managed to break through the perimeter long enough to board the platform and affect the shut down of the MDF.
The elements of Task Force 19 then proceded to engage the elements of the Doenitz Loyalist 1st Defense Fleet. At the end of the day, the 52nd fleet had won the Battle of Sector 001, and had restored the UFP President to his rightful place as head of the UFP.
