The most extraordinary things about this truly incredible tale of World War II are that it hasn’t been told before in English, and that it hasn’t already been made into a blockbuster Hollywood movie. Here are the basic facts: on 5 May 1945—five days after Hitler’s suicide—three Sherman tanks from the 23rd Tank Battalion of the U.S. 12th Armored Division under the command of Capt. John C. ‘Jack’ Lee Jr., liberated an Austrian castle called Schloss Itter in the Tyrol, a special prison that housed various French VIPs, including the ex-prime ministers Paul Reynaud and Eduard Daladier and former commanders-in-chief...