This letter is written by Lieutenant Waller, the Adjutant of the 1st Battalion of Marines (later called the Royal Marines). The Marines, under the command of Major Pitcairn, were part of the expeditionary force that marched to Lexington and Concord, and experienced casualties, on 19 April 1775. This letter, written on 21 June 1775 includes a detailed account of the Battle of Bunker Hill, an action "very fatal to the 1st Battalion." Although his recipient is unidentified, it probably was a friend or fellow officer who would have been familiar with the officers of the battalion.