For what special purpose were these machines used?
Use the last pic as a clue (a distant clue)
SG and Arun did spot the decoy
Answer:
All are inflatable dummy machines used as decoys in World War II, most prominently in Operation QuickSilver (part of Operation Fortitude) under General George Patton who was portrayed by George Scott in the biopic, Patton.
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The bottom picture seems to be from Dr. Strangeglove. Looking closely at the above pictures it seems that all the war equipment shown are fakes and are used as decoys to falsely indicate to the enemy that it is up against a formidable fighting force and therefore is a deterrent to an attack by the enemy.
this is a guess- are they decoys?