The assault frigate Mark I was a modification of the Dreadnaught-class cruiser that was used in the Allied fleet.
As the Alliance began to acquire Galactic Republic-era Rendili StarDrive Dreadnaught-class starships, it found the required 16,000-being crew to be difficult to manage and procure, yet they were in desperate need of warships.
After equipping Dreadnaughts with droids and automated systems to reduce the crew requirement to 5,000 beings, thus rendering the ships usable, Rebel engineers began modifying Dreadnaughts to allow for greater speed and efficiency while retaining the original weapon systems. The final product was only recognizable as a descendant of the Dreadnaught-class by the nose of the ship. Most of the internal structure was exposed to space and two dorsal fins provided added maneuverability.
These modifications removed the internal docking capacity of the Dreadnaught-class, but the ships were equipped with 20 umbilical docking fixtures like those on the EF76 Nebulon-B escort frigate. Unlike the Nebulon escort frigate however, these docking fixtures could not carry other ships through hyperspace. In addition, the assault frigate carried a modified assault shuttle on its back, which was secured in a manner that allowed it to be carried in hyperspace.
The assault frigate had a larger number of weapon emplacements than the original Dreadnaught, but the turbolasers had a shorter range and slower fire rate due to the increased demand on the main power system. The removal of large quantities of hull plating reduced the ship's durability, but slightly stronger shields partially compensated for this.