All 18-year-olds in Britain will have to perform a year of mandatory military or civilian national service if the governing Conservative Party wins the July 4 national election, the party said Sunday. Prime Minister Rishi Sunak pledged to bring back a form of national service for the first time in more than 60 years, seeking to energize his election campaign after a faltering start. The U.K. introduced military conscription for men and some women during World War II, and imposed 18 months...