The impact of the First World War, when many Irish Protestant families lost some or all of their sons at Ypres and the Somme left large numbers of families without heirs and Protestant daughters without Protestant potential husbands, had a devastating impact, an impact augmented separately by Pope Pius X's "Ne Temere" decree, which demanded that all children of Catholic-Protestant marriages be brought up as Catholic (previously, the tradition had been that the boys would be brought up in the religion of their father, the girls in the religion of their mothers). This resulted in a situation where a marriage of a Protestant to a Catholic meant the end of the Protestant line in the family.