The primary circumstance which led to the American Revolution was the French and Indian War. The war was expensive for the British, and Parliament believed the colonies should shoulder at least some of the expense. This led to the Stamp Act, the first attempt to tax the colonies for revenue. The Act led with intense resistance, as the colonists insisted that they should only be taxed by their duly elected representatives; hence the phrase "taxation without representation." Additionally, having fought on their own turf, the colonists had a new sense of identity as Americans and separateness from Britain.
The reaction to the War was the primary catalyst leading to the war. The Tea Act, which restricted the sale of British Tea to agents of the British East India Tea company led to the Boston Tea Party which infuriated Parliament and led to the Coercive Acts. At this point, tempers and feeling were so high that reconciliation was all but impossible.An attempt to reconcile was made following Lexington and Concord with the Olive Branch Petition; however George III refused to even read it.
It is difficult to say if the movement were necessary. It is possible that had Parliament been more sensitive to Colonial concerns, the Revolution might at least have been postponed. Still, the feeling of a separate identity as Americans was probably irreversible and unstoppable. John Adams said it best:
The Revolution was effected before the War commenced. The Revolution was in the minds and hearts of the people; a change in their religious sentiments of their duties and obligations. This radical change in the principles, opinions, sentiments, and affections of the people, was the real American Revolution.