Luftwaffe Ground Attack Units, 1939-45

Influenced by the trench warfare of the First World War, German military planners of the 1930s drew up a new concept designed to bring rapid mobility to the battlefield. This lightning war, or Blitzkrieg, called for particularly close co-operation between air and armoured forces with aircraft primarily employed in the close support role, disrupting the enemy's back area - especially com­munications - and paving the way for deep armoured penetrations by denying him the ability to organise resistance or counter-attack. Should the occasion arise the air force could also support the step-by-step advance of the army by attacking targets directly in the line of advance.
It was already realised as a result of tests carried out at the secret German testing and training establishment at Lipezk in Russia during the 1920s that the precision bombing of pin-point targets could only be achieved by an aircraft releasing its load whilst in a steep dive directly over the target - the dive-bomber. American and Japanese aviation planners were also evincing interest in the idea of the dive-bomber and in 1931, while the US Navy was experimenting with the Curtiss Hawk