On October 10, 1918, the single greatest loss of life occurred in Irish waters when a German u-boat torpedoed the RMS Leinster mail boat on the Kish bank, just fifteen miles from Dún Laoghaire. World War One ended only a month later on November 11, 1917.
501 people perished in the tragedy. Not all the victims were soldiers or military personnel, as civilians, postal staff and ordinary working class people from Dún Laoghaire and Holyhead died. Only 267 bodies were recovered.