Lumsdaine was commissioned lieutenant on 13 July 1776 at Newfoundland and placed in command of the armed boat Postillion 10, a former American privateer, in which he cruised off St. Pierre and Miquelon during the summer of 1777. In July 1778 the commander-in-chief, Vice-Admiral John Montagu, advised that the Postillion, was not fit for sea, and she was eventually condemned and sold at Halifax, Nova Scotia, in September 1779.
On 15 July 1781 he was promoted commander at Newfoundland of the Morning Star 16, which had been the American privateer Royal Louis, and in which he reached Spithead during the middle of October with Rear-Admiral Richard Edwards despatches.
In March 1782 Lumsdaine joined the sloop Merlin 18, sailing under the orders of Vice-Admiral John Campbell from Spithead with twenty-seven vessels of the Newfoundland and Quebec convoy on 17 June. Eight days later the convoy fell in with the Brest-bound Franco / Spanish fleet, and in the ensuing chase eighteen of the merchant vessels were captured but the men of war all made good their escape, whereupon Lumsdaine was sent back to the Admiralty to report the disaster. After spending the summer in Newfoundland he brought home a convoy via Lisbon at the end of the year, and thereafter, as was the custom, went out with Campbell s squadron to Newfoundland in August 1783, returned to Portsmouth from Halifax in November, departed Portsmouth in early June 1784 for the station, returned to Portsmouth on 13 November, and departed for his last year in Newfoundland from Portsmouth with Admiral Campbell s flagship on 19 May 1785 to return to that port on 19 November. Shortly afterwards the Merlin was paid off.
From October 1786 Lumsdaine commanded the Kingfisher 18, going out to the Mediterranean and retaining her through to his posting to the rank of captain on 1 December 1787, being appointed for purposes of rank only to the Pomona 28. In June 1788 he recommissioned the Eurydice 24 at Woolwich, serving initially in the Channel and then going out to the Mediterranean in November. During October 1790 he carried a Moorish ambassador and his suite from Morocco to Constantinople via Gibraltar and Leghorn, and he retained this command until paid off in December 1791.
With the French Revolutionary War looming he recommissioned the Iris 32 at Woolwich in early January 1793, and on 6 March captured the privateer Custine in the North Sea, this being one of several prizes he made during this period. At the end of the month the Iris was in the Humber where she took custody of a convoy for the Mediterranean, and whilst in passage on 13 May she fought a brief and inconclusive action in the Bay of Biscay with an enemy frigate which at first was presumed to be the M d e 36, but later proved to be the Bordeaux privateer Citoyenne Fran aise 32. The Iris lost her fore and mizzen masts as well as her main topmast in the ninety-minute engagement, and her casualties numbered four men killed and thirty-two wounded, one fatally, as opposed to sixteen killed and thirty-seven wounded on the French side. Lumsdaine s first lieutenant, Richard Henry Alexander Bennet, the nephew of the Duchess of Northumberland, was one of the Iris badly wounded, whilst the French captain, Louis de Briolle Dubedat, lost his life. After the action the Iris initially made for Lisbon before later entering Gibraltar under jury masts to be refitted.
In July 1793, having joined the Mediterranean fleet, Lumsdaine was despatched on a vague mission by Vice-Admiral Lord Hood to Tripoli and Tunis in company with the Mermaid 32, Captain John Trigge, and the Tisiphone 18, Commander Thomas Byam Martin, being ostensibly asked to deliver presents and despatches to the local potentates and consuls. Having discovered a French squadron within the harbour at Tunis he ordered an immediate withdrawal, but to his astonishment on returning to the fleet he was brought to a court martial by Hood for disobeying orders, in so much that he had failed to allow the French to capture the Tisiphone and thereby provide the British with the validation to seize all the French shipping on the African coast. Justifiably he was acquitted, and he was therefore present at the occupation of Toulon from August. In March 1794 the Iris arrived back in the Downs with the Smyrna and Gibraltar convoys, and after going around to Sheerness in April Lumsdaine left the frigate.
Within days of removing from the Isis Lumsdaine recommissioned the Polyphemus 64 at Chatham, proceeding to Blakestakes to take on ordnance stores in June, and being sent with one other small sail of the line and four frigates that September in chase of a force of five French frigates and a corvette from Dunkirk which had chased a lugger into the Downs. Returning to Portsmouth in October, the Polyphemus set sail with the West India convoy towards the end of the month but was forced to put into Plymouth on the 29th because of a foul wind. Putting to sea again shortly afterwards, she then headed for Cork which she reached in November.
Remaining on the Irish station and flying the flag of Vice-Admiral Sir Robert Kingsmill when in harbour, Lumsdaine joined the Assistance 50, Captain Nathan Brunton, in escorting the Dutch Overyssel 64 from Beerhaven Bay to Cork in March 1795 following the French subjugation of the Netherlands. During July the Polyphemus led a small squadron out on a cruise from Cork, and on 24 September, being in company with the Santa Margaretta 36, Captain Thomas Byam Martin, she recaptured a homeward-bound merchantman from Jamaica, spending some time thereafter in the expected track of the Jamaica fleet to protect it from a French squadron that had been sent out to intercept it. Returning to Cork on 22 October, Lumsdaine took possession of the Overyssel which had continued to lie at Cork with her colours flying despite the Batavian Republic having declared war on Britain on 15 May. During November the Polyphemus went out on a cruise once more with Martin s frigate to return to port a month later.
After a refit at Plymouth in the summer of 1796 the Polyphemus departed St. Helens in August with Vice-Admiral Sir Hyde Parker s grand convoy, escorting the East India element before parting off the Canary Islands and returning to Plymouth via the Azores at the end of September. Sailing a couple of weeks later for Cork, Lumsdaine again flew Kingsmill s flag before going out on a six-week cruise, during which he took the French privateer Deux Amis 14 in December when in company with the Apollo 38, Captain John Manley. On 31 December the Polyphemus captured the fine French frigate Tortue 44 to the west of Cape Clear in sight of a French 74 and another frigate, these vessels being part of the fleet that had been sent from Brest to invade Ireland. The Polyphemus lost one man killed in the action and the Tortue, which had six hundred and sixty sailors and soldiers aboard, suffered thirty-six casualties. She was later bought into the Navy as the Uranie. Sadly the French transport Juste, which had also struck to the Polyphemus, foundered with over five hundred men aboard. With the French fleet still known to be in Irish waters the Polyphemus promptly returned to sea with Kingsmill s flag but was unable to take any further prizes. Returning to Cork, she remained in port for most of the spring and early summer although she did briefly go out in quest of two large French frigates and a corvette that had chased the Dryad 36, Captain Lord Amelius Beauclerk, into Bantry Bay in March.
In June 1797 the Polyphemus arrived at Plymouth in the midst of the general mutiny, and it was reported that her crew planned to put several officers ashore. After remaining for some time in Plymouth Sound she sailed for Portsmouth in August to collect the East Indies merchant fleet for convoy to Saint Helena, eventually getting away from Torbay on 22 September, having been delayed by adverse winds. The return voyage with the homeward-bound East India fleet began with her departure from St. Helena on 19 December, and giving passage to Captain George Hopewell Stephens, late of the mutinous Tremendous 74, she arrived in the Downs on 29 January 1798. A day later the Polyphemus sustained a great deal of damage when driven aboard by one of the Indiamen in a fierce gale, but this did not prevent her escorting the trade around to Portsmouth shortly afterwards where she remained for several weeks.
On 25 March 1798 the Polyphemus departed Portsmouth to rejoin the Irish station where Lumsdaine had already received the freedom of the City of Cork for his service, and here she re-hoisted Kingsmill flag. In the late summer it was reported that she had been sent with reinforcements to join Admiral Lord St. Vincent s Fleet off Cadiz following Rear-Admiral Lord Nelson s despatch into the Mediterranean. Returning to Cork, she then joined a squadron of five sail of the line that was ordered to cruise in protection of the western coast of Ireland, and returning for the winter to Cork she briefly cruised with Admiral Lord Bridport s Channel fleet off Cape Clear in May 1799 before once more entering port on the 10th. On 20 September she left Ireland for Portsmouth with Kingsmill, and by 18 October was at the Nore from where she sailed up to Chatham on 3 November to be docked and repaired. After coming out of dock on 9 February 1800, she began fitting once more for the flag of Admiral Kingsmill before putting down to Blackstakes on 29 March, but rather than returning to Ireland she was diverted to Yarmouth and Lumsdaine left the command in favour of Captain John Lawford.
It was announced at the beginning of January 1801 that Lumsdaine was going to command the Belleisle 74 in an acting-capacity for Captain William Domett who had joined Admiral Sir Hyde Parker s force destined for the Baltic to serve as captain of the fleet, but in the event it was Captain Charles Boyles who took the Belleisle to sea.
Lumsdaine did not enjoy any further employment but was promoted rear-admiral on 2 October 1807, and vice-admiral on 1 August 1811. He died in South Parade, Bath, on 9 February 1812.
He was regarded as a rough diamond a man of unaccomplished manner but as fine a seaman as any in the service with a ship and crew that were held in the highest regard. In 1805 he owned a property in Parliament Street, Westminster, and the address in his will was given as 24 Somerset Street, Portman Square, London.