The Nagato-class battleships, Nagato and Mutsu, were super-dreadnought-type vessels launched just after the end of the First World War. Mutsu exploded while at anchor in port in 1943. More than 1,000 crew were killed;the cause remains unknown to this day. Nagato survived the war and was sunk during the American nuclear testing at Bikini Atoll; the wreck is widely considered one of the premier diving destinations in the world. This is the illustrated history of both ships, including a historical synopsis, full technical description, and more than 100 photographs and diagrams. Naval historians Lars Ahlberg and Hans Lengerer have established themselves as experts on and specialists in the warships of the Imperial Japanese Navy during WWII. Their work is differentiated by being primarily driven by the utilization of Japanese-language primary source material.