He then pursued graduate work at Yale University, and for his academic success in his first year received the Tew Prize as Outstanding Scholar in History.
Following the attack on Pearl Harbor in December 1941, Holley enlisted in the United States Army and became an aerial gunner, although he still received his A.M. from Yale in 1942.
From 1945 to 1947, Holley was a faculty member at the Industrial College of the Armed Forces before taking a position at Duke University for the remainder of his career.
Holley later identified a theme that ran through these three monographs: "the pace of development for any weapon during the between-war years is chiefly determined by the extent to which its mission or operational function is known and defined."
In that volume, Holley explored procurement in a broad sense: "the computation of requirements, the evolution of internal organization, the relationship and accommodation of conflicts between executive and legislative agencies, the character and capabilities of the aircraft industry, and many other similar facets..." necessary together for a proper understanding the more basic elements of procurement, involving contracts, plant construction, and so on.