How were the American colonies (United States) able to defeat Great Britain in the War for Independence? How did the leadership of George Washington contribute to this victory?

How were the American colonies (United States) able to defeat Great Britain in the War for Independence? How did the leadership of George Washington contribute to this victory? 

Your response should be at least 200 words in length. You are required to use at least your textbook as source material for your response. All sources used, including the textbook, must be referenced; paraphrased and quoted material must have accompanying citations.