McKenna's major work was "The Sand Pebbles" (1962), a 597-page novel later made into the well-known 1966 film of the same title. The protagonist was an enlisted career sailor on a U.S. Navy river gunboat named the "San Pablo" in China during the 1920s. McKenna himself served aboard a river gunboat on the Yangtze Patrol, but about ten years after the events in his novel and of more modern construction ("San Pablo" was an ancient gunboat seized from the Spanish in 1898). "The Sand Pebbles" won the $10,000 1963 Harper Prize Novel and was chosen as a Book-of-the-Month Club selection.