In late , the USN urgently needed more aircraft carriers to face its obligations both in the Atlantic and Pacific. Conversion of existing C3 cargo hulls took time despite their seemingly easy and limited nature, and there was some desperation on how to increase the output.
Kaiser, already famous for the amazing output to deliver Liberty ships suggested the American government to manage the mass construction of a batch of per year. His mass-construction simplification process and technology of continuous assembly and modular approach was, as he argued, adaptable to warships. President Roosevelt has become interested in the project, since in mid, fleet carriers in construction were still far from ready and the need was urgent anyway. The Bogue class having been extensively tested successfully, it was proved that such vessels could provide air cover for the Pacific landing squadrons while continuing to serve in the Atlantic.
Rather than scatter other series between several models of converted freighters, Henry J. Kaiser, the wealthiest holder of the largest and most prolific shipbuilding yards in Vancouver, Canada, proposed to the Admiralty to produce escort carriers in record time less than a year , based on his method of building Liberty Ships.
The Casablanca became the most prolific class of aircraft carriers in history. Although narrower and crampier than the Bogue class, their larger holds made it possible for them to carry more planes and fuel.
They were also much faster thanks to their turbines, coming from fast cargo ships designed to escape U-Bootes. They were actually built in record time, the first, the USS Casablanca, laid down in November and into active service by July whereas the last one, the USS Shamrock Bay, was laid down in November and active in March So in just in 5 months!
