Original: People were especially horrified by the Massacre of Saint Bartholomew (1572), in which some 20,000 men, women and children were massacred, chiefly in Paris, but also throughout France, in a three-day period.
Simplified: People were especially horrified by the Massacre of Saint Bartholomew (1572), in which some 20,000 men, women, and children were massacred, chiefly in Paris, but also throughout France, in a three-day period.