During the First World War, Glenart Castle suffered damaged when she struck a mine in the English Channel northwest of the Owers Lightship on 1 March 1917. She was repaired and returned to service.
Sinking
On 26 February 1918, Glenart Castle was leaving Newport, South Wales, heading towards Brest, France. Fishermen in the Bristol Channel saw her clearly lit up as a hospital ship. John Hill — a fisherman on Swansea Castle — remembered "I saw the Hospital Ship with green lights all around her – around the saloon. She had her red side lights showing and mast-head light, and also another red light which I suppose was the Red Cross light." At 04:00, Glenart Castle was hit by a torpedo in the No. 3 hold. The blast destroyed most of the lifeboats, while the subsequent pitch of the vessel hindered attempts to launch the remaining boats. In the eight minutes the ship took to sink, only seven lifeboats were launched. Rough seas and inexperienced rowers swamped most of the boats. Only 32 survivors were reported. A total of 162 people were killed, including the Captain — Bernard Burt, eight nurses of the Queen Alexandra's Imperial Military Nursing Service, seven Royal Army Medical Corps medical officers and 47 medical orderlies. Of the hospital patients being treated on board, a total of 99 died. The matron of Glenart Castle, Miss Kate Beaufoy, was among those killed in the sinking. Beaufoy was a veteran of the South African War and the Gallipoli campaign. Her family kept her diary and her writings describe life on the ship. Evidence was found suggesting that the submarine may have shot at initial survivors of the sinking in an effort to cover up the sinking of Glenart Castle. The body of a junior officer of Glenart Castle was recovered from the water close to the position of the sinking. It was marked with two gunshot wounds, one in the neck and the other in the thigh. The body also had a life vest indicating he was shot while in the water.
Aftermath
After the war, the British Admiralty sought the captains of U-boats who sank hospital ships, in order to charge them with war crimes. Kapitänleutnant Wilhelm Kiesewetter — the commander of UC-56 — was arrested after the war on his voyage back to Germany and interned in the Tower of London. He was released on the grounds that Britain had no right to hold a detainee during the Armistice.
Memorial
A memorial plaque was dedicated on the 84th anniversary of the sinking, 26 February 2002 near to Hartland Point, with the inscription, "In proud and grateful memory of those who gave their lives in the hospital ship Glenart Castle. Please remember, Master Lt. Cmdr. Burt, Matron Katy Beaufoy, the ships officers, crew and medical staff who died when their ship was torpedoed by UC56 in the early hours of 26th Feb 1918. The ship lies 20 miles WNW from this stone. For those in peril on the sea. R.I.P. Dedicated 26.02.2002". The Scottish military charity Glen Art was founded in 2013 by Fiona MacDonald in honour of her great aunt nurse Mary McKinnon who died while serving on the ship. In February 2018, Glen Art held a memorial concert in Arisaig Scotland commemorating the centenary of the sinking of HMHS Glenart Castle and nurse McKinnon’s death.
