Northern Campaign in the Revolution
Began with the colonists being forced out of Boston in 1775, only to have British loyalists and soldiers take over New York which they would hold for the duration of the War. Militias helped fend off attacks as best they could but rarely were able to do any real damage. British blockaded ports, cutting off supplies, and captured many Norther Cities. This Fighting was difficult because of the intense cold and many simply froze to death.
Battles such as Lexington and Concord were some of the first skirmishes to occur. The North held many key rivers and ports that when liberated from British control could be used to bring supplies in.