Britain’s Prince William and Prime Minister Theresa May, joined by ministers and ambassadors from Allied countries and a former German president, marked on Wednesday the centenary of the Battle of Amiens — a short, bloody and decisive confrontation in northern France that heralded the end of World War I. Chilling readings by May and others recounted the Allied offensive in the eyes of those who fought, including a private, a tank captain, a commander present in the pre-dawn hours of Aug. 8, 1918 for the opening salvos of the combined air and ground assault by soldiers from Britain, Australia, Canada, the United States and France.