7 August 1964 – Photo reconnaissance begins over Vietnam.
Veteran Kenneth V. Jack, in his book Eyes of the Fleet over Vietnam pieces together the chronological history of photo recon in the Vietnam War 
between 1964 and 1972. He writes “Clandestine missions conducted over Laos began [in] 1964″ becoming a congressionally authorized war after the Tonkin Gulf incident in August 1964”, and that “low-level photo reconnaissance played an [equally] important role and was essential to target selection and bomb damage assessment during the Vietnam War”(1)
(1) Amazon