One day, while Gabrielson and Hattendorf were rummaging through the dusty archives of the War College Museum, they pulled open a neglected drawer.
In it lay a workbook with ornate calligraphy, dated 1807. The discovery of William Carter’s Navigation Book, Givet Prison, France, was a real breakthrough for Gabrielson in his master’s research. “When I opened that book, it was a holy-cow moment,” he said. “I literally could not sleep that night.”