The men had been returning home to Lewis, Harris and Berneray having survived the First World War.
Crowds gathered at the memorial site to mark a century since the disaster.
Prince Charles gave a reading at the service and met with descendants, while First Minister Nicola Sturgeon also spoke with members of the public.
They both laid wreaths at a monument which overlooks the scene of the tragedy, as did representatives from emergency services and other organisations.
A note left by Charles read: “In special remembrance of your service and sacrifice.”