In May 1915, Theodate traveled to England to visit the British Society of Psychical Research. She was a passenger on the R.M.S. Lusitania when it was torpedoed by a German submarine. She survived, even after being pulled from the water and left among the dead. One year later, at age 49, she married 51-year-old John Wallace Riddle, a diplomat, whom she had met 12 years earlier through Farmington friend and neighbor Anna Roosevelt Cowles (President Theodore Roosevelt’s eldest sister).