He commanded HMS Tilbury at the Second Battle of Cape Finisterre in October 1747 during the War of the Austrian Succession and commanded HMS Princess Louisa at the Battle of Lagos in August 1759 during the Seven Years' War.

[1] In 1759 he transferred to HMS Princess Louisa and took part in the Battle of Lagos on 18 August 1759.

[1] Harland was promoted to rear-admiral on 18 October 1770 and appointed Commander-in-Chief of the East Indies Station in 1771 remaining there until 1775.

[3] He was further promoted to vice-admiral on 5 February 1776[4] before becoming second in command of the Channel Fleet and fighting at the Battle of Ushant on 27 July 1778.

[1] Harland was appointed to the Board of Admiralty in the Second Rockingham ministry in April 1782.