The increase in the range lethality of weapons, coupled with the new tactics and developing art of camouflage, dictated that an essential element of training for combat forces be directed toward teaching even individual soldiers how to identify an enemy—by shape, by sound, or sometimes by behavior. During World War II, the majority of this training was devoted to recognizing equipment, aircraft, ships, and armored vehicles especially.
To this end, military trainers employed models, printed silhouettes, and even playing cards (with vehicle profiles printed on the faces) as training aids. Special focus was often placed on distinguishing Allied and Axis craft with similar visual characteristics, such as the early models of the North American P-51 Mustang and the German Messerschmitt Me-109. Even so, training was often insufficient to prevent casualties due to fratricide. After a large number of fratricides during the North African and Sicilian Campaigns (especially in surface-to-air situations), the Western Allies went so far as to forgo some element of camouflage to ensure that nervous friendly air-defense gunners on the ground would not shoot at Allied planes during the cross-Channel invasion of France in June 1944. The so-called invasion stripes were a series of broad bands of alternating black and white paint applied to the wings and fuselages of American and British fighters, tactical bombers, and transport aircraft operating in support of the invasion.
IFF was also a device fitted to aircraft to prevent planes from firing on other friendly aircraft and to let ground stations identify them as friendly. The British developed a system whereby their radar identified friendly aircraft by means of an elongated blip on the radar screen. Crews were supposed to turn on these devices when about 40 miles from the British coasts, but many bomber crews kept them turned on over Germany in the false belief that doing so enabled them to jam German radar. In fact, the devices assisted the Germans in vectoring the fighters to intercept them. A competition in electronic warfare developed, with each side attempting to use IFF and other electronic signals to its own advantage and to the detriment of the enemy. Generally speaking, the Royal Air Force remained a step ahead of the Luftwaffe, thanks to superior operations analysis and more emphasis on research. The Germans were also handicapped by extreme security requirements, in which the "need to know" operated against a collegial sharing of useful information.
Success in IFF has always depended on proper coordination. Interservice cooperation was so poor among the Japanese that ground defenses on Iwo Jima could not identify their own aircraft by their signals. Even as recently as the 2003 war in Iraq, the failure to turn on the IFF signal on a British Tornado aircraft may have caused it to be shot down by a Patriot missile.
Robert Bateman and Spencer C. Tucker
Craven, Wesley Frank, and James Lea Cate, eds. The Army Air Forces in World War II. Vol. 4, The Pacific: Guadalcanal to Saipan, August 1942 to July 1944. Washington, DC: Office of Air Force History, 1983.; Hinchliffe, Peter. The Other Battle: Luftwaffe Night Aces versus Bomber Command. Edison, NJ: Castle Books, 2001.; Neillands, Robin. The Bomber War: The Allied Air Offensive against Nazi Germany. New York: Overlook Press, 2001.; Price, Albert. Instrument of Darkness. London: Janes Information Group, 1982.; Searby, John. The Bomber Battle for Berlin. Cambridge: Airlife Publishing, 1991.