John McGrath's Crossing the Line of Departure is a wide-ranging historical overview of that most difficult aspect of military leadership, the art of battle command. McGrath leads the reader through case studies beginning with Alexander the Great leading up to the recent war in Iraq. Among others, he analyzes Napoleon's technique, French and British practices in World War I, the German experience with "Blitzkreig" in World War II, and the Soviet approach to battle command. McGrath also extends his historical analysis to the present day by presenting a description of battle command theory in the "Modular Army" and the Information Age. Through it all, he finds that the key to successful command in battle, particularly in mobile operations, is found in the successful interplay between technology and personal technique. Unlike some pundits today, McGrath does not conclude that information age technology is likely to shift the balance between these poles in favor of technology dependence. The commander's personal sense of where to be on the battlefield, where to locate and how to use his headquarters staffs, and how to communicate with his subordinates have been-and remain today-crucial elements of successful battle command. A 21st century commander has use of technology beyond the comprehension of an Alexander, a Napoleon, or a Guderian; but he will continue to grapple with the same issues of personal presence and technique that they mastered so well. Crossing the Line of Departure brings to the fore insights, trends, and leadership qualities needed for successful battle command. While possessing knowledge of these traits does not guarantee success on the battlefield, their absence will almost assuredly bring defeat.