The Battle of Bunker Hill occurred on June 17, 1775, in the early stages of the American Revolutionary War, when the American forces as a whole were not yet a fully organized army. After the Siege of Boston, the British needed to secure control of the Charlestown Peninsula overlooking Boston from the north across the Mystic River, giving them command of Boston Harbor and ultimately Boston itself. The Committee of Safety learned a few days in advance that the British were going to try to occupy Dorchester Heights and Charlestown Peninsula. The Patriot forces decided to take the offensive, occupy the peninsula, fortify it, and deny the British the advantage of this important and strategic location. Word of British intentions spread fast among the colonies. General Thomas Gage mistakenly assumed that taking the peninsula from untrained colonial "rebels" would be an easy task.