You are using an out of date browser. It may not display this or other websites correctly. You should upgrade or use an alternative browser.
alternatehistory.com
IMO It wasn't so much the fact that the Americans won a few key battles (Saratoga, Yorktown) that secured her independence but the realization that by the British leadership that Britain didn't possess the means to quell such a large rebellion across a vast ocean.
POD New York 1776- Washington realizing that New York is dominated by its local waters but also knowing that the British are going to attack there hits upon the idea to make the British pay for every foot of land they occupy.
Basically Washington turns New York into a break water upon which the vast wave of British military might will be broken.
What happens upon the conquest of New York when General Howe informs Lord North that yet another massive army will be required to destroy the rebellion.