The Spanish Civil War was the first conflict to see real clashes between tanks, employed by both sides of the conflict (at the same time Italy was fighting in Ethiopia, employing a good number of armored vehicles, but against an enemy entirely without tanks). Spain was thus the testing ground for modern warfare between armored vehicles sent from Italy, Germany and Russia. The use of tanks during the Civil War only hinted at some of those aspects that would later make armored forces one of the decisive elements on the battlefield during World War II. This volume will describe the units fielded by the Nationalist and Republican factions.