Panzer is a loanword from the German Panzer, meaning ‘armour’, pronounced [ˈpanʦer] (). It is also used in the compounds Panzerdivision, ‘armoured unit’ and dated PanzerKampfwagen, ‘tank’ or literally ‘armoured combat vehicle’ (the modern synonym is Kampfpanzer, or just Panzer). German Panzer also refers to an animal's protective shell or thick hide, as in Schildkrötenpanzer, ‘turtle shell’. Historically, the word referred to body armour, as in Plattenpanzer, ‘plate mail’, Kettenpanzer, ‘chain mail’, or gepanzert, ‘armoured’.
It derives through the French pancier, ‘breastplate’, from Latin pantex, ‘belly, paunch’, and possibly related to panus, ‘swelling’. The word has been calqued in many other languages, such as Swedish pansarvagn or Finnish panssarivaunu, ‘tracked armoured fighting vehicle’, Danish panservogn, ‘armored vehicle’, but kampvogn means ‘tank’.
Although the post-World War I Treaty of Versailles greatly restricted its military development, Germany started to secretly develop armoured tactics in the 1920s, in cooperation with the Soviet Union (while assisting in the establishment of a Soviet tank-building industry). In the 1930s, the light Panzer I and Panzer II tanks were built primarily for training, and tested in battle during the Spanish Civil War.
At the beginning of the Second World War, German forces gained notoriety for the rapid and successful invasions of Poland, the Netherlands, Belgium and France, and the Soviet Union, in 1939–41. Although the early-war Panzer II, III, and IV were clearly inferior to some of their French and Soviet counterparts, This blitzkrieg (‘lightning warfare’) was made possible by several factors: the German military experience in World War I, their excellent training, integrated communications, coordinated use of airpower, and, perhaps most famously, by the combined-arms employment of integrated infantry and armoured forces, the panzer divisions of the army and Waffen-SS.
As the blitzkrieg began to stall on the Eastern Front, and a mobile war pushed back and forth across North Africa, Germany was was quickly forced into an arms race in armour and antitank weapons. Antiaircraft guns were repurposed for antitank use, thousands of captured antitank guns were marshalled into German service, new inexpensive self-propelled antitank guns put into production, and Panzer IV tanks hastily up-armoured and up-gunned. A new generation of big cats, the heavy Tiger, Panther, and King Tiger tanks were developed and rushed into the battlefield. During the war, the mass of a panzer increased from the 5.4 tonnes of a pre-war Panzer I light tank, to the whopping 68.5 tonnes of the Tiger II. In the meantime, the Soviets continued to produce the T-34 by the tens of thousands, and U.S. industry nearly matched them in the number of M4 Sherman tanks built and deployed in Europe after D-Day.
Throughout the war, the panzer was a key piece of the combined arms doctrines supporting the German blitzkrieg. The tanks were used in every theater of German involvement. Their largest engagement occurred at The Battle of Prokhorovka, which saw about three hundred panzers pitted against five hundred Soviet tanks.