This fully illustrated study pits Germany's Panzer I against the Soviet T-26 in the Spanish Civil War.In 1936, as Spain descended into civil war, both Nazi Germany and the Soviet Union sent tanks to aid the opposing sides, keen to see how they fared in combat. Armed with twin machine guns, Germany's Panzer I fought alongside Nationalist troops, while the 45mm-armed Soviet T-26 took the field with Republican forces, with captured examples soon equipping the Nationalists. In this book, Jacek Zabielski reveals the origins, development and combat history of these two types, which remained in front-line service in 1941 as Hitler's forces invaded the Soviet Union. While both types were soon outclassed by better-armed and -armoured successors, the lessons learned in Spain would shape German and Soviet combined-arms doctrine on the Eastern Front during and after Operation Barbarossa. Featuring specially commissioned artwork, full-colour mapping and archive photographs alongside the authoritative text, this study reveals how the Panzer I and T-26 performed in battle, and their technical and tactical influence throughout World War II.