Around noon, Maj. Gen. William Howe and around 2,500 British soldiers and marines began crossing the Charles River from Boston to Moulton’s Point on the northeastern corner of the peninsula. Once his troops were landed, Howe organized them into two wings and ordered the group on the right, advancing through the gap between Breed’s Hill and the Mystic River, to attack the American soldiers who were lined up behind a low stone wall at the eastern foot of Bunker Hill. While that attack got underway, Howe also instructed the soldiers on his left flank to seize Breed’s Hill. As Howe’s troops neared the American positions, they ran into a devastating storm of musket and rifle fire that felled many of them and forced the survivors to retreat. An unnamed American soldier wrote about that first clash a week later.
"“On the first attck [sic] your [British] troops gave way; they did not expect so heavy a fire. General Howe rallied them; for near a minute he was quite alone; his aid de camp was killed at his side. The officers brought up the men and suffered for their temerity. General Clinton was another corps presently followed. General Putnam, who had not quite 4000 [actually less than 1,500] Connecticut men, thought the whole army was coming and without the least disorder, or even pursued a single step, left Buncker’s Hill [sic-actually Breed’s Hill] and went to another hill [Bunkers Hill], about half a mile further, where he as remained ever since, without the least disturbance.”"
An unnamed eyewitness describing the battle in a letter he wrote on 23 June 1775Commager and Morris, pp. 128-129.