Just a quick update from the American perspective.
After 2 years of staying just out of reach of the Redcoat army I've decided to make a stand at Philadelphia. There will be no Saratoga or Yorktown for me in this game. If I win the current battle it's because I conserved enough strength to keep throwing in replacements to outlast the British. And that is essentially my strategy - Run like hell most of the time, and fight like hell when I choose to make a stand.
My plan for the defense of Philadelphia was to concentrate all my continental artillery around the city to support the 12 or so regiments that will be facing the main British thrust. I'm taking a chance by leaving an open flank near Valley Forge but I want to keep my forces concentrated. If I sense that Ian is going to try an end-around I'll call up some militia to slow him down while I bring in forces that have assembled west of Lancaster.
(this is turn 31 BTW, well before Ian opened his attack)

Grab them by the balls. Their hearts and minds will follow.