The Guards Brigade landed on Long Island on 22 August 1776 and was present in the Battle of Long Island five days later. On 15 September the Guards Brigade took part in the Battle of Kip's Bay, landing in the first wave. Mathew played a significant role at the Battle of Fort Washington on 16 November. With two light infantry battalions under his leadership, he boated across the Harlem River near what is now 200th Street and established a bridgehead. This effort was followed up by Lord Charles Cornwallis with the Guards Brigade, two grenadier battalions, and the 33rd Foot. The advance of this and other columns resulted in a resounding British victory including the capture of 2,818 Americans. After the American victory at Trenton, the 1st Guards Battalion was assigned to Cornwallis for the Princeton Campaign in early January 1777. However, Mathew stayed behind with the 2nd Battalion in New Brunswick, New Jersey. The Guards were involved in several skirmishes during the Forage War.