In the late 1970's, the CSGN program was cancelled. It was understood then that such ships, while very capable, would never be build in enough numbers that they could fulfill the tasks the US navy had to perform. A series of small and medium sized ships was what the USN needed, not giant nuclear combatants.
This decision, left an issue. There was a single nuclear cruiser, still with gun armament as main weapons, that stood on the nomination to be converted to an proto-CSGN. Preparations for its next refueling had already begun and part of the funding was already prepared for this ship that had plenty of hull life left, but which weapon and radar systems needed replacement. This ship was CAN-160. (
http://www.shipbucket.com/forums/viewto ... 63#p187663 )
With the conversion plans now cancelled and even the need for a large cruiser suddenly gone from the fleet requirements, the USN looked for a new purpose for this ship, and they found none, until they asked the Marines.
The marines were in dire need for a ship that could keep up with carrier battle groups or even operate in smaller formations then usually the case with their Tarawa class and iwo jima class ships. The modern warfare environment had showed the value of quick reaction forces performing small scale operations to support existing operations, de-escalate crisis or prepare for larger forces to be landed.
CAN-160's nuclear power plant was both an advantage and an disadvantage for such a task: nobody wanted to risk a nuclear powered ship operating close inshore. However, a solution was found in the design that was finally build and reached operational status in 1982.
LPHN-160 was basically an high speed Iwo Jima type, having large cargo holds in the former gun magazines, a large hangar supporting helicopters and harriers and a full length flight deck. The modular nature of the former cruiser had made this layout possible, the gun magazines being prepared for potential future missile installation meant that converting the magazines to holds posed no structural issues. 2 elevators came from the hangar deck to the flight deck, 2 elevators came from the holds all the way to the flight deck, and 4 smaller elevators came from each of the 4 cargo hold areas (the former main and secondary battery spaces) to the hangar deck level. Between the original main deck and the hangar deck was space for additional crew and marines, with the main 'barracks space' being in the bow in front of the hangar. All in all, her capacity for troops, aircraft and storage was not dissimilar to the Iwo Jima's.
As the ship could reach a top speed of 32 knots and had a cruising speed in all weather conditions of 27 knots, there was no escort ship that could keep up with her. For that reason, the ship received an Oto Melara GDM-C twin 35mm gun, Mk 13 launcher, 2 phalanxes and an Mk 92 fire control system.
Over it's long 2nd service life, the ship would serve many roles, mostly with the marines but sometimes also as harrier carrier, sea control (test) ship or as ASW carrier. When she was finally decomissioned in 2010, her performance would influence the next generation of amphibious ships, the America class, to be build on a more cruiser/carrier like hull and with an 28 knot top speed, allowing those 4 new ships to fill the gap left when the LPHN left service.