Robert Forczyk

“Hitler deployed four panzer groups with a total of seventeen panzer divisions and 3,106 tanks2 for Operation Barbarossa, the invasion of the Soviet Union. In addition, two independent panzer battalions, Pz.Abt. 40 and Pz.Abt. 211, were deployed in Finland with 124 tanks (incl. twenty Pz.III). The 2 and 5.Panzer-Divisionen were refitting in Germany after the Greek Campaign in April 1941 and were in OKH reserve. Otherwise, the only other extant panzer units were the 15.Panzer-Division with Generalleutnant Erwin Rommel in Libya and two panzer brigades in France. No other panzer units were in the process of forming in Germany. Consequently, the OKH was committing virtually all of the available German panzer forces to Barbarossa, with negligible reserves and limited monthly production output to replace losses. In mid-1941, German industry was producing an average of 250 tanks per month, half of which were the Pz.III medium tank. Combat experience in France and Belgium in 1940 indicated that the Germans could expect to lose about one-third of their medium tanks even in a short six-week campaign, which Hitler regarded as acceptable losses. Furthermore, German industry had no tanks beyond the Pz.III or Pz.IV in advance development. The Heereswaffenamt (Army Weapons Office) only authorized Henschel and Porsche to begin working on prototypes for a new heavy tank four weeks before Operation Barbarossa began, and this program had no special priority until after the first encounters with the Soviet T-34 and KV-1 tanks in combat.”
― Robert Forczyk, Tank Warfare on the Eastern Front, 1941–1942: Schwerpunkt

“As a general rule of thumb, about 5 per cent of tanks in a given unit will break down for mechanical reasons after a 100km road march, although most can be repaired within a few hours. Just three years before Barbarossa, nearly 30 per cent of the 2.Panzer-Division’s tanks broke down on the unopposed 670km road march to Vienna, along good roads.3 If the panzer divisions suffered a similar scale of combat losses as in the 1940 Western Campaign, no more than 10–20 per cent of the original panzers would be likely to reach their objectives.”
― Robert Forczyk, Tank Warfare on the Eastern Front, 1941–1942: Schwerpunkt