of Charlestown, had commanding views of Boston and its outer harbor. The harbor was vital to the British, as the Royal Navy, at first under Admiral Samuel Graves, and later under Admiral Molyneux Shuldham, provided protection for the troops in Boston, as well as transportation of supplies to the besieged city. Early in the siege, on June 15, the British agreed on the plan of seizing both of these heights, beginning with those in Dorchester, which had a better view of the harbor than the Charlestown hills. It was the leaking of this plan that precipitated events leading to the Battle of Bunker Hill. Neither the British nor the Americans had the daring to take and fortify the heights; but both armies knew of its strategic importance in the war. When Washington took command of the siege in July 1775, he considered taking the unoccupied Dorchester Heights, but rejected the idea, feeling the army was not ready to deal with the likely British attack on the position. The subject of an attempt on the heights was again discussed in early February 1776, but the local Committee of Safety believed the British troop strength too high, and important military supplies like gunpowder too low, to warrant action at that time. By the end of February, Knox had arrived with the cannon from Ticonderoga, as had additional supplies of powder and shells. Washington decided the time was right to act. Fortification Washington first placed some of the heavy cannons from Ticonderoga at Lechmere's Point and Cobble Hill in Cambridge, and on Lamb's Dam in Roxbury. As a diversion against the planned move on the Dorchester Heights, he ordered these batteries to open fire on the town on the night of March 2, which fire the British returned, without significant casualties on either side. These cannonades were repeated on the night of March 3, while preparations for the taking of the heights continued. On the night of March 4, 1776, the batteries opened fire again, but this time the fire was accompanied by action. This cannonade was continued on three successive nights, and while the British were focused on this, the Americans made preparations to implement a plan devised by Rufus Putnam to break the long siege. The American objective was to get cannon onto Dorchester Heights, and fortify the position. However, the ground was frozen, so digging was impossible. Putnam, who had