The anniversary was the most potent reminder of how grievously the people of Northern Ireland suffered over the course of decades because of sectarian hatreds.
The emotional scars of that terrible day in 1972 are still raw.
A lengthy inquiry into the deaths, and even an apology in 2010 by the then Prime Minister, David Cameron, failed to bring any sense of closure to the issue, with many unanswered questions about what happened still remaining.
Yet there is some hope to be drawn from the anniversary. That it was able to be commemorated peacefully is a measure of how far Northern Ireland has come.
It is also a reminder that working to maintain that peace is an ongoing process.