March 18 (UPI) -- On this date in history: In 1922, Mahatma Gandhi was sentenced to six years in prison for civil disobedience against the British rulers of India. In 1925, the worst tornado in U.S. history roared through eastern Missouri, southern Illinois and southern Indiana, killing 695 people, injuring thousands of others and causing $17 million in property damage. In 1937, a natural gas explosion at a public school in New London, Texas, killed almost 300 people , most of them children. In