W J ASTORE—The nation’s founders knew there’d be national emergencies that would require a larger “standing” military (i.e., not just state militias of “minutemen”), but they wanted to prevent a state of permanent war, which they attempted to do with the two-year appropriation clause. They were well familiar with history and all those hundred years’, thirty years’, and seven years’, wars. By giving the people (Congress) the power of the purse, they hoped to prevent those long wars by cutting off open-ended funding.
Of course, today that doesn’t apply. The AUMF (authorization for the use of military force) that dates from 2001 is used to justify a state of perpetual war and the funding of the same. Congress has abnegated its responsibility to check overweening Executive power for war-making, but actually it’s worse than that: Congress has joined the Executive branch in pursuing perpetual war.