The 4th volume of our authoritative series, German Naval Artillery is fully dedicated to calibres from 20mm to 40mm. The first chapter deals with the 40mm Bofors gun, so effective that it was introduced on the decks of warships as an anti-aircraft weapon. In the second chapter we meet the famous German anti-aircraft 37 mm caliber gun, widely used on all Kriegsmarine warships, with all its development versions and successors described. Finally, we look at the 20 mm caliber guns, starting with the first copies of prototype versions which were systematically upgraded before being put into mass production. This is a particularly helpful publication for modellers, and with all the photographs, drawings and 3D graphics included, every reader will come away with a more accurate knowledge of the various guns. A bi-lingual publication, with text and captions in both Polish and English, this book contains a rare visual and technical insight into the AA guns used on the mighty warships which terrorised the Allied battle and shipping fleets of the Atlantic Ocean.