20th+: Camouflage, Deception, Espionage, Intelligence

Military deception (MILDEC) is an attempt by a military unit to gain an advantage during warfare by misleading adversary decision makers into taking actions detrimental to the adversary. This is usually achieved by creating or amplifying an artificial fog of war via psychological operations, information warfare, visual deception, or other methods. As a form of disinformation, it overlaps with psychological warfare. Military deception is also closely connected to operations security (OPSEC) in that OPSEC attempts to conceal from the adversary critical information about an organization's capabilities, activities, limitations, and intentions, or provide a plausible alternate explanation for the details the adversary can observe, while deception reveals false information in an effort to mislead the adversary.

Deception in warfare dates back to early history. The Art of War, an ancient Chinese military treatise, emphasizes the importance of deception as a way for outnumbered forces to defeat larger adversaries. Examples of deception in warfare can be found in Ancient Egypt, Greece, and Rome, the Medieval Age, the Renaissance, and the European Colonial Era. Deception was employed during World War I and came into even greater prominence during World War II.In modern times, the militaries of several nations have evolved deception tactics, techniques and procedures into fully fledged doctrine.

5 Famous WW2 Covert Operations .
1. Operation Mincemeat
2. Operation Eiche
3. Operation Gunnerside
4. Operation Greif
5. Operation Fortitude South

Operation Bodyguard: Operation Fortitude North; Operation Fortitude South including Operation Quicksilver I-IV;

Operation Bodyguard was the code name for a World War II deception plan employed by the Allied states before the 1944 invasion of northwest Europe. The plan was intended to mislead the German high command as to the time and place of the invasion. The plan contained several operations, and culminated in the tactical surprise over the Germans during the Normandy landings on 6 June 1944 (D-Day) and delayed German reinforcements to the region for some time afterwards.

German coastal defences were stretched thin in 1944, as they prepared to defend all of the coast of northwest Europe. The Allies had already employed deception operations against the Germans, aided by the capture of all of the German agents in the United Kingdom and the systematic decryption of German Enigma communications. Once Normandy had been chosen as the site of the invasion, it was decided to attempt to deceive the Germans into thinking it was a diversion and that the true invasion was to be elsewhere.

Planning for Bodyguard started in 1943 under the auspices of the London Controlling Section (LCS). A draft strategy, referred to as Plan Jael, was presented to Allied High Command at the Tehran Conference in late November and approved on 6 December. The objective of this plan was to lead the Germans to believe that the invasion of northwest Europe would come later than was planned and to expect attacks elsewhere, including the Pas-de-Calais, the Balkans, southern France, Norway and Soviet attacks in Bulgaria and northern Norway.

Operation Fortitude was the code name for a World War II military deception employed by the Allied nations as part of an overall deception strategy (code named Bodyguard) during the build-up to the 1944 Normandy landings. Fortitude was divided into two sub-plans, North and South, with the aim of misleading the German High Command as to the location of the invasion.

Both Fortitude plans involved the creation of phantom field armies (based in Edinburgh and the south of England) which threatened Norway (Fortitude North) and Pas de Calais (Fortitude South). The operation was intended to divert Axis attention away from Normandy and, after the invasion on 6 June 1944, to delay reinforcement by convincing the Germans that the landings were purely a diversionary attack.

Operation Quicksilver was a military deception operation performed during the Second World War. Undertaken by the Allies in 1944, the operation threatened an invasion of France in the Pas de Calais region through the simulation of a large Field Army in South East England. Quicksilver formed part of the Operation Fortitude deception, itself part of the strategic Operation Bodyguard plan. The key element of Quicksilver was to convince the German that "First United States Army Group" (FUSAG) commanded by General George Patton would land in the Pas-de-Calais for the major invasion of Europe, after the landings in Normandy had lured the German defenders to that front. (FUSAG was a genuine army group headquarters which later became Omar Bradley's 12th Army Group, but was given a fictitious role and many non-existent divisions for purposes of deception.)

Juan Pujol García, known by the British code name Garbo and the German code name Arabel, was a double agent loyal to the Allies who played a crucial role in the deception by supplying Germany with detailed information from a network of non-existent sub-agents supporting the idea that the main invasion was to be in the Pas-de-Calais.

Quicksilver was subdivided into six subplans numbered I through VI:

Quicksilver I was the basic "story" for Fortitude: the First United States Army Group, based in the southeast of England, was to land in Pas-de-Calais after German reserves were committed to Normandy.
Quicksilver II was the radio deception plan of Quicksilver, involving the apparent movement of units from their true locations to southeastern England.
Quicksilver III was the display of dummy landing craft, including associated simulated wireless traffic and signing of roads and special areas. The landing craft, built from wood and canvas and nicknamed Bigbob's, suffered from being too light. Wind and rain flipped many over or ran them to ground.
Quicksilver IV was the air plan for Quicksilver, including bombing of the Pas-de-Calais beach area and tactical railway bombing immediately before D-Day.
Quicksilver V was increased activity around Dover (giving impression of extra tunneling, additional wireless stations), to suggest embarkation preparations.[12]
Quicksilver VI was night lighting to simulate activity at night where dummy landing craft were situated.

Operation Bodyguard succeeded and the Normandy landings took the Germans by surprise. The subsequent deception suggesting that the Normandy landings were a diversion led Hitler to delay sending reinforcements from the Pas-de-Calais region for nearly seven weeks (the original plan had specified 14 days).

https://www.iwm.org.uk/history/d-days-parachuting-dummies-and-inflatable-tanks .

Dummy tanks > .