two assaults on the colonial positions were repulsed with significant British casualties; The third and final attack carried the position after the defenders ran out of ammunition. The colonists retreated to Cambridge, leaving the British in control in charge of Charlestown but still besieged in Boston. The battle was a tactical victory for the British, but it proved to be a sobering experience, involving more then twice the casualties than the American had incurred, including many officers. What was one result of the battle described in the source?