;kaku class are generally regarded as being the most-successful carriers designed by the Imperial Japanese Navy. They became operational just prior to the Pearl Harbor attack in December 1941, and their combat records are impressive. Compared with the preceding aircraft carrier designs, they represented a great design leap, combining excellent striking power with good protection. Even by the US Navy these ships were rated highly. During the Pacific War the two ships of the class participated in all carrier battles with the exception of Midway, Shōkaku being lost in the Battle of the Philippine Sea and Zuikaku off Cape Engaño (Battle of Leyte Gulf) in 1944. This is the history of their design and construction, and it relies heavily on Japanese source material and includes numerous photos and drawings.