This excellent report has been professionally converted for accurate flowing-text e-book format reproduction. Historians and other military analysts often use the term "strategic initiative." Most assume a common understanding of this term, but the concept has been neither carefully defined nor examined in depth. This thesis contributes to the elimination of that gap by answering the question: What factors lead to shifts in strategic initiative during the conduct of modern, conventional war? The Russo-German War of 1941-45 and the Pacific War of 1941-45 provide the historical evidence for this study.Both conflicts progressed through three distinct phases in which the Axis combatant first seized the strategic initiative, which then fell into dispute, and eventually shifted to control of the Allied combatant. Four factors contributing to strategic initiative have been examined for each phase of each war: resources, quality of intelligence, strategic acumen, and operational and tactical methods. These elements of military effectiveness reflect each nations war-making capacity, knowledge, wisdom, and technique. The relative advantages each side enjoyed in each category are compared to determine which factors more significantly influenced shifts in strategic initiative and how each component acted upon the others.The heart of the study focuses on the transition into, conduct during, and the transition from the second phase of each war, where the actual shifts in initiative occurred. Strategic acumen led the hierarchy of factors that influence strategic initiative in war. The side that better matched its goals with its capabilities, took advantage of opportunities, and planned more realistically reaped the largest rewards. Good intelligence proved to be a key enabler to the clear judgments that are the hallmark of strategic acumen and placed second in the hierarchy. Resources, followed by operational and tactical methods, placed third and fourth respectively. Nevertheless, each of these components influenced the possession of and shifts in strategic initiative. Intelligence, resources, and operational and tactical methods all contributed to strategic acumen as well, either restraining or constraining a combatants abilities. In summary, this study reveals that a four-fold hierarchy of superior wisdom, knowledge, capacity, and technique drives shifts in strategic initiative in modern, conventional war.