> Whether it is called “Department of War” or “Department of Defense”, it’s still the same organization maintaining the same mission operating under the same budget.

The mission of the Department of War, which was its name pre-WW2, and the mission of the Department of Defence (post-WW2) is completely different: this is evidenced by the number of military personnel in the two time periods (and the draw-down in personal post-1990, after the Cold War ended):

* https://www.statista.com/statistics/1066986/us-armed-forces-...

* https://en.wikipedia.org/wiki/File:US_military_personnel_and...