Hartington’s mother invited Kennedy to Christmas, and soon after, Hartigto proposed.

The couple wed in an unassuming civil ceremony in the Caxton Hall Registry Office on May 6, 1944.

Four months later, WWII would forever alter their lives.

Kathleen “Kick” Kennedy smiling

Billy was called to service as a member of the British army on June 13, 1944.

William “Billy” Cavendish, Marquess of Hartington, and Kathleen Kennedy smiling at each other

Kathleen, Rose, and Rosemary Kennedy smilig