Deception has been a part of warfare for thousands of years and in many ways it has been raised to an art form.  A successful deception, such as the mythical army assigned to Patton in the run-up to the Normandy Invasion, can make all the difference on whether a military operation is an utter failure or an overwhelming victory.

With the advent of aerial photo reconnaissance, the threat from aerial attack became a serious issue. One of the lessons of WWI was that recce aircraft were frequently soon followed by bombers and it paid off to make efforts to hide new structures, lay out fake trench systems, and lures to bring in unwary attack aircraft.  When observation balloons became targets, German and French anti-aircraft forces learned to send up unmanned balloons as decoys, surrounded by dozens of AA gun positions that could quickly shred any fighters that came too close to the bait.

WW2 raised the bar for decoys, and all the major belligerents utilized them.  In the United States, entire factories were covered with camouflage netting and elaborate fake streets and neighborhoods were erected on the roofs of factories to give the elusion of urban living, while fighters and bombers rolled off production lines a few feet below.  Factories churned out inflatable tanks and there were combat units that only existed in falsified radio traffic.

Few nations took decoying to the level of the Germans.  This is due to their being under air attack from 1939 to 1945, with literally thousands of bombing raids in those six years.  Many decoying techniques were tried and met with some measure of success.  Beginning in 1939, the Luftwaffe began setting smoke pots and fires some distance away from known targets, resulting in hundreds of thousands of bombs being dropped on open country.  When marauding RAF nightfighters began to attack landing German aircraft, fake airfields were built, with flare paths and rigged lighting to simulate a plane over the runway. 

The advent of free-ranging long range fighters such as the Mustang and Thunderbolt meant that literally any target in the Reich was open to their attacks. Everything was a target, from factories and ports down to individual bicyclists, and airfields in particular became magnets that were frequently attacked by roving fighters. Easily identified from the air, airbases were struck harshly and repeatedly, resulting in many lost aircraft.

The Luftwaffe poured considerable efforts into "Maskrikova" (this Russian term has been used for decades to describe military deception techniques) building Ersatz fields near active air bases. To lure eager Allied fighter pilots,  light-weight hangars were built in fields and many different types of "Attrappen" (decoys) were assembled to give the appearance that the base was operational.  The two main types of decoy aircraft were cobbled-together junk airframes and stick-and-canvas shapes that at least looked realistic to pilots passing over at high speed and low altitude. 

These decoy airfields were truly flak-traps and it was common for them to be protected by dozens to hundreds of light and medium flak guns, manned by highly trained crews.  The Allies lost many pilots attacking these sites, trading their lives for a few strikes on a wooden target