Sidney Forrester Mashbir (12 September 1891 – 13 June 1973)[2] was a senior officer in the United States Army who was primarily involved in military intelligence.

Mashbir then held several posts in intelligence positions, taking credit for catching the first German spy in the United States, before departing for on a four-year assignment as a language officer to Japan in 1920.

However, following the attack on Pearl Harbor, Mashbir was re-enrolled in January 1942 to lead the Allied Translator and Interpreter Section of Southwest Pacific Area, where he quickly rose to the rank of colonel.

[4] Sidney's father was Professor Eliazar S. Mashbir, a Russian immigrant who was well-educated and became the first Russian-speaking attorney to practice law in New York City.

[7] Mashbir is also credited with investigations as a coast defense intelligence officer at Fort Hamilton, which uncovered the first German spy to be apprehended in the United States, Paul Otto Kuhn.

[3] Following World War I, Mashbir held a position teaching military science and tactics at Syracuse University, where he first considered studying the Japanese language and culture.

Consequently, Mashbir resigned in 1923 to pursue business interests and undercover secret intelligence operations, under the impression that he could be reinstated in the Army when his work was done.

[3][12][13] He managed to rejoin the Military Intelligence Division G-2 Reserves, but only spent one year in active duty beginning in the summer of 1927 during which time he updated the Order of Battle documentation on Japan (War Plan Orange).

In a misunderstanding that would come close to damaging his career irreparably once more, Mashbir was investigated in Hawaii and, influenced by the military attaché suspicions, a prejudicial report based upon erroneous assumptions was delivered on 24 June 1937.

[3] Colonel Mashbir was advised on 25 February 1939 that he was disenrolled from the Military Intelligence Division G2 Reserves for failure to report on the specified day for physical examination.

[3][15] Despite Mashbir's dismissal, the outbreak of hostilities in World War II between Japan and the US, led to him being immediately sought after by the Signal Corps due to his military experience, wide technical skill and knowledge of the Japanese language.

He was sworn in for active duty on 24 January 1942 and sent to Brisbane, Australia, and later Manila, Philippines to co-ordinate the inter-service joint Australian/American Allied Translator and Interpreter Section (ATIS), within the Southwest Pacific Area (SWPA).

[3][18][19] He was made famous at the time in the motion picture and still photograph of the preliminary surrender negotiations at Manila, as the man who pushed the ink-well, indicating that General Richard K. Sutherland should correct the Japanese Instrument of Surrender; and also as the man who thumbed the Japanese Lieutenant General Torashirō Kawabe along as he attempted to shake hands.

[22] In his autobiography, Mashbir explained that he was not permitted to shake hands, and that it would have been rude to point, which ultimately led to the awkward thumbing motion that was photographed.

[1] Two years after retiring, Mashbir published a 374-page memoir describing his military and intelligence career titled: I Was an American Spy (Vantage Press.

[23][3] In Chapter 13, "The Nisei" (whom Mashbir used as translators in ATIS) he pays tribute to Military Intelligence Service (MIS) soldiers in these words: "The United States of America owes a debt to these men and to their families which it can never fully repay.

"[24] Because of the highly classified top-secret nature of ATIS missions, the work of many MIS soldiers and knowledge of Mashbir and his colleagues was unknown to the public during WWII, and even decades afterwards.