Yes. I think there is some truth to that statement. It is difficult for a country to conduct a war over seas in a foreign country. For example, you can use the US and its wars in Afghanistan. The locals know the country and conventional warfare does not work very well. I think Washington did make some key decisions. I watched a show on some of the battles in Boston. Washington hauled a bunch of cannons in winter to the top of a hill in Boston. He could hit the British ships in the harbor from the high ground. However, the British cannons could not hit the top of the hill. That was an example of Washington's generalship.
Okay so why do you think that the British lost?
I think they lost because they were over extended and could not possess all the territory because it cost way to much money.