I think the real name should always have been Department of War and Defense.
Dept of Defense has always seemed like total bullcrap to me. Was it “Defense”when we invaded Grenada, Panama, Iraq, Afghanistan, and any other number of countries?!? Vietnam?? All our invasions in Latin America?? Or when we lob missiles at Iran or Yemen? Was it Defense when we gave Great Britain refueling rights on Ascension Island off of Brazil during the Malvinas War or Intel?
I think Department of War is more honest than Department of Defense. It’s not as politic obviously.