This paper argues that an overlooked pathway via which major powers are drawn into conflict with each other is via competition over small states and territories. When a major power seeks to monopolize a subordinate, preventing others from pursuing their interests in its territory, norms of open subordinate governance are challenged. To address this violation, threats and force may be used. Moreover, the monopolizer is perceived as having revisionist preferences for international order, meaning future interactions are understood in this context. Three pathways to war open up, firstly, monopolization itself may involve the significant use of force, secondly, major powers may immediately respond with force, and thirdly, future interactions will involve greater suspicion and threat-making, increasing the probability of war. This argument is evaluated through quantitative examination of rising power disputes between 1816 and 2010, and comparative case study analysis of the Spanish-American and Russo-Japanese wars. Contestation of the norms of subordinate governance play an important role in shaping the probability of major power conflict, and provide insight into the behaviour of the major powers in the contemporary international order.