Panzerkampwagen IV and its Variants 19351945 Book 2. This book is the final documentation on the Panzerkampfwagen IV series, the most often-built German tank of World War II and presents the exact chronology of the vehicles development from 1935-45, plus many hitherto unknown and pioneering test vehicles. The authors discuss the origin of the Large Tractor, the so-called Neubau New-Built Vehicle and the attempts in 1944 to install the 7.5 cm Kampfwagenkanone 42 L/70 of the Panther onto the Panzer IV. The authors have dedicated an entire chapter to armament, and action in all wat theaters.