Scotland and Wales did not travel to Dublin to play Ireland because of escalating political tensions in the wake of Bloody Sunday.
Although the remaining fixtures of the schedule were fulfilled, as both Ireland and Wales won all their matches, neither could claim the title.
To fill the gap of the missing two fixtures, France played a friendly match in Dublin (in addition to the scheduled match in Paris).
[1] This tournament saw France play its last matches at its decades-long home ground, Stade Yves-du-Manoir in Colombes.
The opening of the rebuilt Parc des Princes that June saw France move its Five Nations matches to that ground.