In Army lingo the office that is called Deputy Chief of Staff For Plans and Operations - is nicknamed DSCOPS.
From politico-military planning, to operational control of all Army units inside the United States, it was the heart of military long range thinking and planning for future wars or planning for them.
So I was assigned to the small staff of midgrade - from Major to Colonel - Army officers who did more thinking than doing. And reports to the 'Army Planner' - brigadier general who provided both the Lieutenant General who oversees the 'operations' of Army units inside the US, and the Chief of Staff of the Army who, in his dual hat as highest ranking Army officer, and as a member of the Joint Chiefs of Staff who report to the Secretary of Defense and through him to the President as Commander in Chief.
That Planning office dates far back, but was especially signifcant leading up to and through WWII, as it worked to insure that military planning and operations were within the scope of the war objectives and policies set down by the President.
There was no separete 'Air Force' then - only an Army Air Corps as part of the Army - thus under General George C Marshal and a Navy under the Chief of Naval Operations, under which the Marine Corps operated.
General Eisenhower, during WWII was somewhat frustrated by that increasingly obsolete arrangement, which he set right as President getting Congress to pass a Defense Department (not War Department) Reorganization Act that created the Unified and Specified Command structure, whereby all military forces OUTSIDE the United States were divided into geographical regions called Unified Commands - headed by 4 star generals who might be from any service - Army, Navy, or Air Force - but who reported directly to the Secretary of Defense (not the Joint Chiefs) and through him to the President.
Then some special commands - like the Strategic Air Command - with the main nuclear - air borne or by ICBM missile - were Specified Commands.
And that left the Service departments Army, Navy, Air Force with uniformed Chiefs of Staff, and Secretaries of the Services responsible, not for military 'operations' but for recruting, training, service personnel and units in the active and reserve services to get them ready for war, and provide them with the weapons and logistics of war.
As the United States ended WWII as the most powerful and wide ranging nation on earth (with the arguable exception of the Soviet Union with its nuclear forces) that militarily sound - with clear chains of command and military responsibility from the individual soldier all the way to the Present - arrangement served us well for a very long time.
So I was in a Pentagon office, where some other Classmates were also - where we thought and studied about the nature of international armed conflict and war, the US actual and likely policies toward such conflicts, and made recommendations to the Chief of Staff of the Army how US Army forces should be organized, trained, and readied for any contingencies.
(At one time, while I was in the Pentagon I met Air Force Colonel Brent Scowcroft. He was doing essentially what I was doing as a staff officer, but for the senior officers of the Air Force. He made the remark he envied the Army for having a dynamic Policy and Plans staff, which the Air Force did not have. Of course he went on to become a General officer and the head of the White House's National Security Council.
He had very much to 'do it alone' for the Air Force. While the Army had a full complement of bright - yet field and even combat tested mid grade officers in DCOPS Policy and Plans, who could produce brilliant analysis for the most senior officers - like Harold Johnson. }
We thought in longer range terms than almost any other officers (perhaps except those attending the War Colleges which, however, were just 'individual' officers professional views, while the Pentagon staff's views were aimed at making real changes in current Armed forces). And, depending on our professional military views and projections - honed, unlike academics - by actual participation in and command of US Army units in combat, and after years of development as staff officers and commanders with constant contact with 'peer' (by age, rank, and military experience) fellow officers, we were the up and coming 'next' generation of war fighting commanders and staffs.
With that setting of context, now I will tell what I did, on a day to day basis as one of the active 'thinkers' of the US Army. Who responded to questions by more senior (general officer level) staff officer, generated papers or studies on our own.
First, where was my Pentagon Office?