I would say that at that time in history Guerilla Warfare was seen as very violent when compared to the traditional warfare of the time. However, this was probably the only way the colonists had a chance of winning the war.
While considered ruthless, the guerilla style or hit and run warfare tactics were utilized by the Americans. They could not beat the British in traditional warfare. They were outnumbered and outgunned and out trained. For the Americans to march across a battlefield to meet the British in the traditional mode of European style warfare was practically suicide. The Americans had to learn to work around their disadvantages.
Battle tactics during the American Revolution truly followed a "civilized" approach to warfare. As mentioned in previous posts, guerilla activity (most notably by Francis Marion and Ethan Allen) was considered among the most ruthless tactics employed. Even the limited presence of Native American tribes failed to employ any of the brutalities (scalpings, disembowelments, etc.) often pictured in films.
As with any insurgency, even in the modern day, the American Revolutionary Army was more typically effective operating in small units on battlefields of their own choosing. They were also better at seizing their supplies than they were at procuring their own through channels.
The degree of hit and run tactics varied from place to place depending on the amount of traditional training and experience they had, and the preferences/techniques of their individual commanders.
A very interesting paper was written about the way that most guerrilla tactics or the armies that practice them. One of the things it pointed out was the way that armies that found success with those tactics then tried to adopt the tactics of the dominant army. The Americans tried this and were often thwarted because the British and their mercenary allies were of course far more proficient in this form of warfare. But the pressure to conform to standards of warfare, even when not effective, are very powerful and the revolution was another example of this.
George Washington was so outmanned during the Revolution that his main goal was to evade the British whenever possible. He fought very few pitched Battles. As noted above, Nathaniel Greene fought a major battle at King's Mountain, South Carolina during which General Ferguson, the British commander was killed. Also in the South, General Francis Marion, known as the "Swamp Fox," conducted guerrilla warfare against British and Tory troops. Although some British commanders were alleged to have used brutal torture against prisoners of war, there is no evidence of inordinate violence in the war.
There was no one tactic used invariably by the American in the Revolution. It is true that they used some amount of hit-and-run, guerrilla type tactics. This was done most notably in the South as Greene's army moved around the countryside, fighting small battles and causing the British to have supply problems. However, the Americans did fight pitched battles when they felt they had the capacity to do so. This was seen most notably at Saratoga and at Yorktown.
Here's a link that might help: