The US would lose most of its forces to friendly fire...
LOL!, Nice 
Its a question which got stuck in my mind, if the commonwealth of nations were to unite back to the days before, would they still be a superpower? my ansewer is yes, even bigger then amercia, its easy to take over and control one nation, maybe even 3 for the USA, but the nations under the commonwealth are too vast, and some have very large armies.
The USA advanatge of placement of there troops would be pointless, becuase of the placement of the commonwealth of nations. Canada would be the first to go, but if they recived help from Britain, then they would last or would be able to hold the USA for much longer. And not forgetting Britain has the best trained troops then any other country in the world, and the best special forces diverisons , e.g SAS, Royal Marines etc.
Our miltary force has downsized a lot in over a century, from being the biggest superpower in the world, to now the 5th in miltary expendienture, it should be Britain lending support to other nations such as soilders etc, not america, Britain owned 1/3 of the world, but somehow they let there reponisbilites slip, and becuase of this, they let Amercia take the lead Role.
God damn yanks, why did they have to revolt 