Editing Blitzkrieg (section)

===Environment===
The concepts associated with the term ''blitzkrieg'' (deep penetrations by armor, large encirclements, and combined arms attacks) were largely dependent upon terrain and weather conditions. Wherever the ability for rapid movement across "tank country" was not possible, armored penetrations often were avoided or resulted in failure. The terrain would ideally be flat, firm, unobstructed by natural barriers or fortifications, and interspersed with roads and railways. If it were instead hilly, wooded, marshy, or urban, armor would be vulnerable to infantry in close-quarters combat and unable to break out at full speed.{{Citation needed|date=November 2018}} Additionally, units could be halted by mud ([[thaw (weather)|thawing]] along the Eastern Front regularly slowed both sides) or extreme snow. Operation Barbarossa helped confirm that armor effectiveness and the requisite aerial support depended on weather and terrain.{{sfn|Winters|2001|pp=89–96}} The disadvantages of terrain could be nullified if surprise was achieved over the enemy by an attack in areas that had been considered natural obstacles, as occurred during the Battle of France in which the main German offensive went through the Ardennes.{{sfn|Winters|2001|pp=47–61}} Since the French thought that the Ardennes unsuitable for massive troop movement, particularly for tanks, the area was left with only light defences, which were quickly overrun by the ''Wehrmacht''. The Germans quickly advanced through the forest and knocked down the trees that the French had thought would impede them.{{sfn|Frieser|2005|pp=137–144}}