When Robert Longworth’s new vessel was launched from a Grand River shipyard on Prince Edward Island in June 1865 no one could have imagined that more than half a century later she would play an important role in the Great War.
Longworth, a Charlottetown shipbuilder and broker, named the new vessel the Thirza, a Hebrew name from the bible which could be translated as “she is my delight.” A small ship, she was only 104 feet long and 23 feet in breadth and displacing under 200 tons. She was a rather plain vessel although with a figurehead featuring a female bust. The vessel was rigged as a brigantine: she had two masts — the foremast rigged with square sails and carrying a fore and aft rig on the mizzen. This was a common rig for Island built vessels at the time as it required a smaller crew and was more maneuverable than either a schooner or a fully-rigged ship. Longworth clearly built the ship for sale in Great Britain and before she left the Island to sail across the Atlantic in August 1865 (probably with a cargo of timber) he empowered the Pitcairn mercantile firm in London to sell her for anything over £1,800. A little more than a year later she was purchased by a number of men in Faversham, a market town in Kent, on the Thames Estuary downstream from London.
The Thirza appears to have had an unremarkable history as a coastal vessel serving ports all around England for the next fifty years, carrying cargos to and from small harbours; coal, timber, bricks – anything that that was easier and cheaper to move by water rather than by rail. Her age was remarkable at a time when small sailing vessels were easily used up and was a testament to the skills of her P.E.I. builders and by the maintenance by her Faversham owners. Although remarkable the Thirza was not unique. In fact the Sela, another brigantine, which was built on the Island in 1859 was not broken up until 1976 after a service of 117 years.
The Thirza’s life as a coastal trader changed following the outbreak of the Great War in 1914. England was dependent on the continued sea borne commerce to supply her people and her war effort. The Germans were dedicated to disrupting the commerce and forcing Great Britain to its knees. Most histories of the was at sea focus on the destruction of large cargo and passenger steamers but the German Navy knew that fishing and coastal vessels were also essential to keep the British population fed and industries in full war production.
The great German weapon of the war was the submarine with its torpedoes and its ability to surprise its targets. However the submarines could carry relatively few torpedoes and they were expensive so captains held them back and whenever possible sank their victims with surface gunnery, especially when the vessels were smaller and slower ships incapable of fighting back.
One of the tools the British developed was to create disguised armed merchantmen which had the appearance of helpless vessels but which were in reality ships capable of sinking a submarine on the surface. These were known as “Q ships” named for Queenstown in Ireland where they were first put into action.
The Q ship was an ordinary steamer or sailing vessel that had hidden armament. They were in effect decoy vessels set to attract U-boats. They out-gunned the deck guns of the submarines. The Q ships had elaborate disguises to conceal the weapons including false deckhouses and lifeboats behind which hid powerful guns. The crews wore civilian clothing and acted as merchant sailors when stopped by U-boats, even faking abandoned ship drills when threatened.
In August 1915 the Thirza was purchased by the British Admiralty and became the HMS Probus. With a volunteer Royal Navy crew she served as a decoy vessel armed with two 12 pound guns and two 6 pound guns. To confuse the enemy she operated under several names including the Thirza, Elixer, Ready and Q-30. June of 1917 found the Probus as part of a convoy of 12 sailing ships lead by one armed trawler. A sailing convoy requires a lot of sea room to prevent collisions and the first 12 ships were spread across three miles while the Probus lagged 4 miles behind looking like a straggler. The ruse attracted a German submarine intent on an easy kill. The U-boat was itself disguised as a ketch with a fake mast and sails and the Probus was soon under fire. Then dropping the pretense of a merchant ship the White Ensign was run up and the disguise for the guns removed and the Probus returned fire, hitting the submarine several times. The U-boat subsequently submerged. However the blow was not final and after about fifteen minutes it resurfaced and again approached the Probus. By this time the armed trawler from the convoy had turned and was approaching the area forcing the sub to flee. This was fortunate for the Probus as the wind had dropped making it almost impossible to work the vessel to windward and making her a sitting duck. To add to her problems the propeller of her low powered auxiliary engine had become fouled in her log line and was effectively out of action. Although the U-boat escaped, the Probus had succeeded in luring it away from the convoy. The slow-moving sailing Q-ships were an effective escort for sailing convoys and allowed armed steam vessels to be employed elsewhere. In addition, the vessels carried freight as would a normal ship and paid for themselves over and over. It was not unusual for the Probus to earn more £1000 a month.
During the course of the war the British used upwards of 200 Q-ships, the vast majority of which were steamers, some of which were actually small warships such as Flower class sloops disguised as steamships. About 37 were sailing vessels. The ships sank a total of 14 U-boats and damaged 60, but 27 Q-ships were lost in the war.
The exchange between the brigantine and the submarine was captured in a sketch and later an engraving by marine artist William Lionel Wyllie who also made other sketches of the vessel.
After the war the Probus was returned to commercial service and her original name. She disappears from the registers in 1920 and was probably broken up.
Sources: One of the most accessible histories of the Q-Ships and their successes was published in 1922. Q-Ships and Their Story was written by E. Kebler Chatterton and was until recently out-of-print and has recently been re-published but thanks to the miracle of the internet is available on-line on the internet at: Q-ships and their story : Chatterton, E. Keble (Edward Keble), 1878-1944 : Free Download, Borrow, and Streaming : Internet Archive. Details of the encounter with the U-boat are found at pages 186-189 of the volume. For information about the British coastal sailing fleet (including several P.E.I. – built vessels) see Basil Greenhill. The Merchant Schooners. Naval Institute Press 1988.