He is most remembered for his accounts of his work for the British military during the Second World War, in which he claimed to have created large-scale ruses, deception, and camouflage in an effort to defeat the Nazis.

According to one account, he convinced skeptical officers, including inspector of training Viscount Gort, of his bona fides by camouflaging a machine gun position in plain sight and creating the illusion of the German warship Graf Spee on the Thames using mirrors and a model.

He found the training boring, asserting in his book that "a lifetime of hiding things on the stage" had taught him more about camouflage "than rabbits and tigers will ever know".

[5] The camoufleur Julian Trevelyan commented that he "entertained us with his tricks in the evenings" at Farnham, but that Maskelyne was "rather unsuccessful" at actually camouflaging "concrete pill-boxes".

[7] These included tools hidden in cricket bats, saw blades inside combs, and small maps on objects such as playing cards.

By February 1942, it became clear that this command was not successful, so he was "transferred to welfare"—in other words, to entertaining soldiers with magic tricks.

Forbes describes it as lurid, with "extravagant claims of cities disappearing, armies re-locating, dummies proliferating (even submarines)—all as a result of his knowledge of the magic arts".

Forbes also notes that David Fisher, writing in his biography of Maskelyne, The War Magician, was "clearly under the wizard's spell".

Hambling denies Maskelyne's supposed concealment of the Suez Canal: "[I]n spite of the book's claims, the dazzle light[s] were never actually built (although a prototype was once tested)".

[21][22] On 24 June 1926 Maskelyne married Evelyn Enid Mary Home-Douglas (died 24 March 1947), who had worked as a magician's assistant in his stage show.