I am sure it was in 1960. My grandfather was involved in this exercise and he died at 23 in 1965. Here is some information from the newspaper article found it was held at Fort Bragg N.C August 13-28. it involved 30,000 troops as phase one of the Strategic Army Corps exercise. if that helps any.
PFC Triplett was I think in the Army. The picture with him was taken in Aug 1960.