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 been a millwright , devised a plan using chandeliers ( heavy timbers , ten feet long , used as frames ) and fascines . These were prefabricated out of sight of the British . General John Thomas and about 2,000 troops quietly marched to the top of Dorchester Heights , hauling tools , the prefabricated fortifications and cannon placements . Hay bales were placed between the path taken by the troops and the harbor in order to muffle the sounds of the activity . Throughout the night , these troops and their relief labored at hauling cannon and building the parapet overlooking the town and the harbor . General Washington was present to provide moral support and encouragement , reminding them that March 5 was the sixth anniversary of the Boston Massacre . By 4 a.m. , they had constructed fortifications that were proof against small arms and grapeshot . Work continued on the positions , with troops cutting down trees and constructing abbatis to impede any British assault on the works . The outside of the works also included rock-filled barrels that could be rolled down the hill at attacking troops
Boston Massacre
Boston Massacre
Fortification of Dorchester Heights