The American Civil War presented an exceptional state of affairs in modern warfare, because strong personalities could embed their own command philosophies into field armies, due to the miniscule size of the prior US military establishment. The effectiveness of the Union Army of the Tennessee stemmed in large part from the strong influence of Ulysses S. Grant, who as early as the fall of 1861 imbued in the organization an aggressive mind-set. However, Grant’s command culture went beyond simple aggressiveness – it included an emphasis on suppressing internal rivalries among sometimes prideful officers for the sake of winning victories. In the winter of 1861 and the spring of 1862, the Army of the Tennessee was organized and consolidated into a single force, and, despite deficits in trained personnel as compared to other Union field armies, Grant established important precedents for both his soldiers and officers that would resonate even after his departure to the east. The capture of Vicksburg the following summer represented the culminating triumph of that army, cementing the self-confident force that would later capture Atlanta and win the war in the western theater.

From 1914 through 1945, the British Army displayed extraordinary heroism on the sharp end, while leadership at the higher levels was less than satisfactory. To a considerable extent, this was a result of a peculiar regimental culture that had developed over the nineteenth century when the army served as a constabulary force with its regiments spread across the empire. The result was a military culture that focused downward and that devalued the serious study of war as crucial to the development of military professionalism. The result was that at the sharp end, British regiments produced extraordinary brave and tough soldiers. However, at the higher levels, British generalship was less than impressive. The two exceptions to that rule, Field Marshals William Slim and Bernard Law Montgomery, spent substantial portions of their careers during the interwar period either as students or as instructors at the staff colleges. Moreover, both were serious students of military history.