By AD 1900, coal propelled the industrialized world. In the following decades, however, it was rapidly superseded by oil, a shift with enormous consequences for the global balance of power. In Oil and the Great Powers, historian Anand Toprani (US Naval War College) examines the effect of this shift on the strategic planning of two of the era’s “great powers”—Great Britain and Germany.

As Toprani explains, geography played a key role in this story. While both Britain and Germany were blessed with abundant coal, neither enjoyed oil reserves like those of the United States, Russia, Mexico, Venezuela, or the Middle East. Though both powers had begun transitioning their navies to oil power by 1914, the First World War was the great catalyst, thanks to the dawn of the internal combustion engine. Toprani stresses that oil was a contributing, not a decisive, resource in the war’s outcome, but its growing ubiquity ensured that the next great conflict would certainly be an “oil war.”

The end of the war in 1918 left the two powers in different positions to prepare for this. As one of the victors, Great Britain had the luxury of a range of options and soon adopted a two-pronged strategy: gaining control of Royal Dutch Shell and developing the oil reserves in the areas of the Middle East newly within the British sphere of influence. Toprani sees this as a fundamental error made by the British, to wit, confusing “energy independence” with “energy security.” While the former offered the mirage of self-sufficiency (in Britain’s case, in an imperial context), the latter required “secure access to supplies at stable prices” (16). That ultimately proved to be the more important goal. The British realized this only after the outbreak the Second World War made them painfully aware of the vulnerability of the supply lines between Middle Eastern oil and its consumers in Great Britain. This revelation made a mockery of their interwar efforts and presuppositions.

Britain spent much of the interwar period pursuing the elusive goal of “controlling” the oil fields directly or indirectly in the complacent atmosphere of the 1920s; the mounting threat of war from 1933 onward bared the flaws in Whitehall’s plans. For all the effort the British devoted to securing their claims to the oil in the Middle East, France’s defeat and Italy’s entry into the war in June 1940 throttled the Mediterranean supply routes needed to make their shipping math work. As a result, Toprani observes, the United States and Venezuela became Britain’s largest wartime suppliers of oil; the financial costs of this “exposed the shallow foundations of [Britain’s] imperial pretensions following World War I” (133).

Britain was not alone in this regard; Germany, too, found itself dependent upon distant oil supplies. Here the circumstances were very different, however. Interwar Germany lacked an empire that might supply it with oil. Instead, it placed its hopes on synthetic fuel. Though the National Socialist regime fully backed the development of a synthetic fuel industry, Toprani traces the origins of this effort back to the Weimar regime, which saw in hydrogenation a chance to help domestic coal producers while lessening Germany’s dependence on imported petroleum. Limiting oil imports had the added benefit of conserving their limited foreign exchange, which was of immense benefit to Germany’s rearmament after the Nazis took power in 1933.

Synthetic fuel was, in fact, never seen as a comprehensive solution in an of itself. Throughout the 1930s, the Nazis strove to limit civilian consumption and boost refining capacity; in 1938 they began to woo Romania in hopes of securing a reliable wartime supplier on the European continent. The sum of these exertions gave Germany a narrow margin of reserves, enough for the blitzkrieg style of warfare the Wehrmacht famously espoused. Yet the outbreak of war in September 1939 soon exposed the limits of Germany’s achievements, as consumption proved higher than anticipated, synthetic production plateaued, and access to Romanian oil was constrained by a transportation bottleneck. While the Germans mitigated these difficulties by seizing fuel stocks from their defeated foes, their stalemate with Britain proved an unending drain on their oil resources. Moreover, their success on the battlefield had created a unanticipated problem: how to supply their newly won possessions with the energy needed to exploit them.

As a result, by autumn 1940 Germany faced a imminent crisis for which the conquest of the Soviet Union seemed the only solution:

Solving that crisis required a swift conquest of the Caucasian oilfields. The failure to achieve this exacerbated Germany’s situation by adding the demands of an ongoing campaign in the east to the drain on their energy resources. Unlike Britain, however, Germany lacked an ally who might supply the needed oil.

Anand Toprani has canvassed a broad range of materials in British, German, and American archives. He is certainly also conversant with the relevant secondary literature in both English and German. Oil and the Great Powers should command the attention of anyone interested in modern international history, World War II, and the eclipse of Britain and Germany as great powers by the United States and the Soviet Union: both whom enjoyed, among other advantages, the energy security that the British and Germans could not match.