[Prophet in the wilderness]

There was a competition in 1966 from the Government for a large transport plane, and Lockheed won the contract in 1966.
The first C-5A was delivered to the Transitional Training Unit at Altus Air Force Base in Okla, in December 1969.
The first operational C-5s were delivered to the 437th Military Airlift Wing, Charleston Air force base, S.C. in June 1970.
As side note, both Lockheed and Boeing, both were competing for that government contract in 1966 for the very large lifter and transport airplane.
Lockheed won the contract, but, Boeing having lost that contract still put the design of the very large lifter and transport aircraft to good use ( also, with the input from Juan Tripp - C.E.O. of Pan AM Airlines ) and out from that came the 747 program.

[Eric in the Ozarks]

Interesting trivia.