There might not have needed to be a huge POD in terms of battles, wars or conquests.
Melvin Bragg in his book 'The Adventure of English' (which is an excellent history of the English Language) writes that 'after independence, some Americans it is said were swept away by enthusiasm and agreed that America should cut off completely from Britain and adopt another language altogether - French, Hebrew, even Greek were suggested.'
Something to consider perhaps, although it seems a little far fetched, as Bragg himself says.