We walked past the Royal Charter memorial last year, but an Irish Sea ferry, Leinster, sank with an even greater loss of life.

RMS Leinster was an Irish ship operated by the City of Dublin Steam Packet Company. She served as the Kingstown-Holyhead mailboat until she was torpedoed and sunk by the German submarine UB-123, which was under the command of Oberleutnant zur See Robert Ramm, on 10 October 1918, while bound for Holyhead. She sank just outside Dublin Bay at a point 4 nautical miles (7.4 km) east of the Kish light. The exact number of dead is unknown but researchers from the National Maritime Museum believe it was at least 564; this would make it the largest single loss of life in the Irish Sea.

On October 18, 1918 at 9.10 a.m. UB-125, outbound from Germany under the command of Oberleutnant zur See Werner Vater, picked up a radio message requesting advice on the best way to get through the North Sea minefield. The sender was Oberleutnant zur See Robert Ramm aboard UB-123. Extra mines had been added to the minefield since UB-123 had made her outward voyage from Germany. As UB-125 had just come through the minefield, Vater radioed back with a suggested route. UB-123 acknowledged the message and was never heard from again. The following day, ten days after the sinking of the RMS Leinster, UB-123 detonated a mine while trying to cross the North Sea and return to base in Imperial Germany. There were no survivors.