It might draw european involvement, but end the war? What Mac McDowell and Davis failed to understand was that the capture of a capital would not have the decisive effect that it had in prior wars. Washington's value was as a port and connecting with the B&O apart from industry and rail connections the richmond-petersburg area was equally useless to the
CSA. The taking of WDC or Richmond might not end the war, but the long term disruption of the opposing govt might end it. With no centralized command, coordination, large scale reinforcement and communication become difficult if not impossible, thus rendering the advantage to the occupying side.
Respectfully,
Matt