Thrown into the heart of war with little training--and even less that would apply to the battles in which they were engaged--the units of the 112th Cavalry Regiment faced not only the Japanese enemy, but a rugged environment for which they were ill-prepared. They also grappled with the continuing challenge of learning new military skills and tactics across ever-shifting battlefields. The 112th Cavalry Regiment entered federal service in November 1940 as war clouds gathered thick on the horizon. By July 1942, the 112th was headed for the Pacific theater. As the war neared its end, the regiment again had to shift its focus quickly from an anticipated offensive on the Japanese home islands to becoming part of the occupation force in the land of a conquered enemy. James S. Powell thoroughly mines primary documents and buttresses his story with pertinent secondary accounts as he explores in detail the ways in which this military unit adapted to the changing demands of its tactical and strategic environment. He demonstrates that this learning was not simply a matter of steadily building on experience and honing relevant skills. It also required discovering shortcomings and promptly taking action to improve—often while in direct contact with the enemy.