The Assault Frigate Mk. II was a further development of the Dreadnaught-class heavy cruiser modification project, which produced the Mark I Assault Frigate. Although the modification procedures allowed for some variation between individual craft, the most common assault frigate configuration had large dorsal engine fins, and could operate with less than a third of the Dreadnaught's crew requirements (4,820 nominal/ 1600 minimum) thanks to extensive automation systems.
The Assault Frigate Mark II incorporated a shield generator based on Mon Calamari designs, as well as Calamari shield subsystems that allowed an increase in shield power for short periods.
Using the design of the Dreadnaught-class heavy cruiser as a starting point, the original Assault Frigate was created. This design was further modified by dissident engineers at Rendili StarDrive, creating the Mark II. The Mark II shirked much of its predecessors' history however, moving away from the standard Dreadnaught model toward a more original design.
After the Rebellion sympathies of this splinter group was discovered within their company, Rendili StarDrive brought an end to the Mark II project. Though the Mark II did not disappear completely, further production slowed to a trickle. However, the Mark I remained in common use even in the time of the New Republic.
As seen in Star Wars: Empire at WarEdit
The Assault Frigates are very effective against corvette and light frigate class vessels, most notably, Tartan patrol cruisers, Acclamators, Broadside Missile Cruisers, and Crusader Gunships. The Assault Frigate also seems to have an advantage against Victory Cruisers, due to their Shield Recharge special ability, which effectively nullifies the ion cannon on the Victory (unless the Victory boosts its firepower). Assault Frigates can also fend off fighter attacks fairly well with their laser cannons. They are also roughly 20% faster than a Nebulon-B at sublight speeds, giving them the capability to rapidly charge an enemy and out-maneuver the bulkier and slower Imperial frigates in hit-and-run attacks.
When comparing the Alliance Assault Frigate and Nebulon-B, the Assault Frigate is not much of a step up in terms of durability. The Assault Frigate's armor and shielding are only slightly better than the Nebulon-B frigate's. While the Assault Frigate is a proven warship against corvettes and other frigates, it suffers from an ineffectiveness against capital ships and high level space stations, and a vulnerability to bombers due to its low number of hardpoints.