Although he became a respected soldier, fighting with Horatio Nelson in the Napoleonic Wars and later rising to the rank of general before becoming aide de camp to Queen Victoria, Menzies is best remembered for the founding of Newcastle, New South Wales and the successful commencement of its settlement between the age of 21 and 22.

He was attached to Vice Admiral Horatio Nelson's squadron off Boulogne, on France's Atlantic coast and was repeatedly involved in attacking shore batteries and engaged in skirmishes with French boats.

[3] In December 1803 Menzies sailed to Australia on board HMS Calcutta, which was transporting some convicts to New South Wales and then others to form a new settlement in Tasmania (then known as Van Diemen's land).

[3] Menzies was aboard the ship in Port Jackson, Sydney on 5 March 1804 when a rebellion involving a number of convicts broke out[3] in the area of Castle Hill.

Governor Phillip Gidley King, faced with a need to prevent future outbreaks of this nature, hanged the nine leaders of the 300 rebels involved and ordered the establishment of a new settlement to segregate the Worst of the Irish sent here for Sedition from the other convicts.

The Commission signed by the Governor noted: Whereas it is expedient, in consequence of an instruction from His Majesty's Principal Secretary of State for the Colonies and War Department, as well as from existing causes, that the settlement at the Coal Harbour and Hunter River, now distinguished by the name of Newcastle, in the county of Northumberland, should be re-established without loss of time...: You are, therefore, hereby required and directed to take upon you the charge and command of the said settlement; and I do hereby charge and command all His Majesty's subjects that may be within our command to obey your directions, and you to obey all such Orders and directions as you may from time to time receive from me, or any other your superior officer (sic), according to the rules and discipline of war.

[4]Menzies resigned his commission in relation to his detachment of Royal Marines and formed an expedition of skilled personnel including the surgeon James Mileham, Isaac Knight whose role was to be superintendent of the convicts, John Tucker a store-keeper, the botanist George Caley, Ferdinand Bauer an artist, and eleven military guards.

[2][4] Other than the general Commission provided by the Governor, Menzies was instructed to use the convicts to get "as many coals as possible", cutting cedar, clearing ground for cultivation and "to enforce a due observance of religion and good order".

[3] After a year establishing Newcastle, Menzies submitted his resignation to Governor King so that he could "return to England" and his "duty in the Royal Marines".