As a junior officer he served on George Anson's voyage around the world and commanded the landing party which sacked and burned the town of Paita in November 1741.

[1] In February 1741 Brett transferred to Anson's own ship, the fourth-rate HMS Centurion, as second lieutenant, and in this capacity, he commanded the landing party which sacked and burned the town of Paita in November 1741.

[1] During the Jacobite rising Brett saw action on 9 July 1745, when as captain of the fourth-rate HMS Lion he exchanged fire with the French ships Elizabeth and the Du Teillay.

Brett was forced to wait until December for Cambridge to be declared fit to put to sea, and then it was not until February 1757 that she was equipped with her full complement of cannon.

[6] Brett's orders were to join Admiral Edward Boscawen's Western Squadron protecting British interests on the North America and West Indies Station.

Disease spread so fast among the crew that Cambridge was forced to return to Plymouth after only one year at sea so that the sick could be discharged to local hospitals.

[6] He was appointed to the Board of Admiralty as Senior Naval Lord[7] in the Chatham ministry under Sir Edward Hawke in December 1766, holding office until 28 February 1770.