If we are talking about Washington directly then yes he won his battle via conventional warfare but when we talk about the war that he symbolizes as the leader, there is little denying that guerrilla warfare is what disheartened the British troops and emboldened the militias and locals. The following article highlights how important small skirmishes and hit and run tactics where to the revolutionary war. http://www.independent.org/publications/article.asp?id=1489