A memorial dedicated to the victims of a Japanese merchant ship sunk by the German navy in the final days of World War I was unveiled Thursday in Wales.

The churchyard ceremony, which took place exactly 100 years after the sinking, was attended by descendants of the victims and members of the British royal family.

Only 30 of the 240 sailors and passengers on board the Hirano Maru survived when the ship was torpedoed by a German U-boat in the Irish Sea on Oct. 4, 1918, just over a month before the peace armistice was declared to end the conflict. As Japan was one of the U.K.'s allies, its merchant vessels were targeted by the German navy.