This method was used extensively in both world wars and the Korean war. The armed forces commandeered railroads, communications, ships, and coal, for example. D.C. Private property rights were effectively abolished. With a constitutional foreign policy, most of these resources would have been available for private investment. We are a much poorer country because they were not.
War also means more government control of labor, with the draft the preferred means.
Soldiers whose terms of service were set to expire have been forbidden to leave, tantamount to a partial draft. The war economy means government takeover of private resources and people. This would easily be recognized without war. Suppose that the president on his own authority, suddenly expanded government control of the economy. People would have much less freedom, and would have to pay much higher taxes.