Operation Bodyguard was the code name for a World War II deception strategy employed by the Allied states before the 1944 invasion of northwest Europe. Bodyguard set out an overall stratagem for misleading the Oberkommando der Wehrmacht as to the time and place of the invasion. Planning for Bodyguard was started in 1943 by the London Controlling Section, a department of the war cabinet. They produced a draft strategy, referred to as Plan Jael, which was presented to leaders at the Tehran Conference in late November and, despite scepticism due to the failure of earlier deception strategy, approved on 6 December 1943.

Military deception (MILDEC) is an attempt by a military unit to gain an advantage during warfare by misleading adversary decision makers into taking action or inaction that creates favorable conditions for the deceiving force. 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.