Field Marshall Viscount Slim holds a special place in modern military history. He soundly defeated the Imperial Japanese Army in Burma in 1945, retaking the strategically important Burma Road, and safeguarding the Chinese Theater from sure culmination. By all accounts, Slim is a military genius, having achieved this notable victory even after the Japanese 15th Army pushed Allied troops all the way back to India. The historical records attribute Slim's success to his superior ability to lead soldiers in combat, but they tell only half the story. By tracing Slim's implicit process of theoretical thinking, using an observe, interpret, hypothesize, test, and prescribe action framework, this story demonstrates that Slim's genius came from a combination of his abilities to lead and think theoretically. Specifically, in the case of Slim, his ability to think theoretically afforded him the opportunity to develop a new operational approach-a paradigm shift of sorts-and his leadership made it possible to motivate his men to employ that approach. The author asserts that it is the presence of these two abilities in a single man that make him a superior military commander.