This article attempts to situate the approach to World War I within the context of the uneven and combined development of 19th-century European capitalism. Through a comparative analysis of German and British development within the context of the epochal transition from feudalism to capitalism, the article proposes that existing historical materialist and Realist understandings of the roots of World War 1 are inadequate. Realist analyses, stressing the primacy of 'geopolitics', fail to provide a convincing explanation of the precise origins of German bellicosity. Instead they assume that expansionist German behaviour was an inevitable consequence of systemic anarchy. Historical materialist accounts, preferring a sociological explanation, overstate the importance of systemic capitalist crisis and the European-wide escalation of class struggle for understanding the genesis of the war. Utilizing Trotsky's concept of uneven and combined development, I contend, enables a more comprehensive understanding of the origins of the conflict.