Sea Power Theory and the First World War

In the decades prior to the outbreak of the First World War in 1914, the American naval officer and historian Alfred Thayer Mahan published a series of works explaining why navies mattered. His most famous tome, The Influence of Sea Power Upon History, was published in 1890 and remains the traditional starting point for studies of sea power theory to this day. The book helped to propel Mahan to celebrity status in the ensuing years. His ideas were admired by powerful individuals in Europe, notably Kaiser Wilhelm II, and helped him to forge relationships with policymakers in the United States too, not least President Theodore Roosevelt. The core of his ideas concerning the relationship between land power and sea power was perhaps most succinctly expressed in The Interest of America in Sea Power, Present and Future, in which he claimed that ‘control of the sea, by maritime commerce and naval supremacy, means predominant influence in the world; because, however great the wealth product of the land, nothing facilitates the necessary exchanges as does the sea’. While Mahan looked to the age of sail – and the rise of the British Empire – to understand sea power, his message, as the title of this book suggested, was one for the present day.

Across the Atlantic Ocean, a Reader in Geography at the University of Oxford was also mulling the future utility of sea power. On 25 January 1904, this academic – Halford John Mackinder – visited the Royal Geographical Society in London to deliver a lecture. It was published later that year in The Geographical Journal as ‘The Geographical Pivot of History’, and like Mahan’s work has since become a classic text in the canon of strategic thought, acting as a key element in the foundation of ‘geopolitics’. He sought to shock the Edwardian elites in attendance with a bold thesis: the ‘Columbian epoch’ – the age that Mahan had described in which navies had been critical to the development and maintenance of power in the international system – was over. His lecture has commonly been interpreted to claim that, by exploiting the enhanced mobility afforded by new technologies such as trans-continental railway networks, states with large armies would now dominate the international order. Germany and Russia, working together, might come to control all of ‘Euro-Asia’, marshalling a vast pool of resources that would enable them to destroy any challenger to their hegemony, on land or at sea. Mackinder’s nightmare scenario posed difficult questions for the future of the British Empire. At the centre of a maritime ‘world-system’, underpinned chiefly by the might of the Royal Navy, Britain could not hope to match a Russo-German combination on land. With the advantages of sea power seeming to ebb away at the dawn of the twentieth century, the sun must set on the British Empire sooner rather than later.

In the popular conception of the First World War, this process began to play out a decade later. Britain fought a disastrously expensive war on the European continent against Germany and its allies.

In the process of defeating this rival, Britain destroyed the foundations of its own strength anyway. It built a large army against the supposed traditions of the ‘British way in warfare’, resulting in enormous casualties and economic ruin. The battles of the Somme and Passchendaele were etched irrevocably on the national psyche, bywords for futility and waste. Meanwhile, the Royal Navy – and its French, Russian, Italian, and from 1917 American counterparts – appeared to achieve little, their expensive battleships floating idly, unable to win a decisive victory over enemy fleets. To some historians, these events rendered Mahan’s analysis irrelevant, while Mackinder’s prophecy seemed to have been proven. The War had been fought and won on land – although it was unclear how and indeed if any state, other than perhaps the United States, was genuinely a victor.

In recent years, a number of important works have been published re-assessing this interpretation of the First World War. Despite the cost, Britain helped to win the First World War – a coalition effort – by skilfully developing a first-rate army through the maelstrom of 1916 and 1917, producing victory in the field in 1918. By 1919, Britain had expanded its global empire and remained the greatest power on earth into the 1920s. Yet the role of sea power in helping to achieve this victory remains controversial. Misunderstandings of Mackinder’s 1904 lecture also persist. Revisiting Mackinder’s own verdict on the War helps to shed light on contemporary views of sea power.

In 1919, Mackinder – who had since been elected as the Member of Parliament for Glasgow Camlachie – returned to the ideas set out in ‘The Geographical Pivot of History’ in an expanded work titled Democratic Ideals and Reality: A Study in the Politics of Reconstruction. He stated that he was revisiting ‘these themes at greater length… because I feel that the War has established, and not shaken, my former points of view’. Mackinder aimed this book directly at the ‘peacemakers’ – chiefly the leading politicians of Britain, France, Italy, and the United States – hoping to influence the outcome of the Paris Peace Conference. He argued that the League of Nations must be founded not merely on democratic ideals, but the realities of power. Consequently, how the War was won must be understood accurately. He therefore reminded his readers of the timeless significance of the sea, from The Book of Genesis to the works of Mahan himself. Mackinder then discussed the ‘impressive… results of British sea-power’, arguing that ‘never before has sea-power played a greater part than in the recent War’. Ultimately, he did not believe that the influence of sea power was waning – the War had demonstrated its continued significance – but he suggested instead that it ought to be organised more efficiently to counter the growing threat from the ‘World-Island’ of continental Europe, Asia and Africa.

Mackinder’s recommendations reflected a wider belief in the utility of sea power as a force in the international system following the events of the First World War. Although Mahan had passed away in 1914, his fellow American naval officers continued to propound his theories. Rear Admiral A.C. Dillingham was therefore reminiscent of both Mahan and Mackinder when he stated at the end of the War that ‘the influence of sea power has never been more strongly illustrated by the example we have before us in the case of the Central Powers today’.

Critical to this was the blockade, underpinned by the Allied navies, which cut the Central Powers off from overseas markets and resources. While the blockade remains a controversial subject among historians, a number of important civilian and military leaders similarly concluded that it had played a crucial role in the Allied victory. For example, David Lloyd George, the British prime minister, rated blockade as almost as important as the Allied armies in defeating the Central Powers. Ferdinand Foch, the French generalissimo, thought that the blockade was equally responsible for victory, while the American General Tasker Bliss believed that it had played an even more significant role than that. Sea power had meanwhile enabled the Allies to access the American money market and resources from overseas, and bring these to bear in Europe so to destroy the German field army. As Mackinder put it, Allied naval supremacy meant that ‘German troops in the German Colonies were isolated, German merchant shipping was driven off the seas, the British expeditionary force was transported across the Channel without the loss of a man or a horse, and British and French supplies from over the ocean were safely brought in’. He was therefore able to conclude that ‘we have been fighting lately, and in the close of the War, a straight duel between land-power and sea-power, and sea-power has been laying siege to land-power. We have conquered’. While the exact scale of the contribution of sea power to victory in the First World War remains debated by historians today, contemporary strategic thinkers like Mackinder were more certain, and believed that it must continue to influence the course of history.

Bibliography and further reading

Ashworth, Lucian M., ‘Realism and the spirit of 1919: Halford Mackinder, geopolitics and the reality of the League of Nations’, European Journal of International Relations 17:2 (2010), pp. 33-51

Darwin, John, The Empire Project: The Rise and Fall of the British World System, 1830-1970 (Cambridge: Cambridge University Press, 2009)

Dillingham, A.C., ‘What Steps in Organization and Training Should be Taken to Maintain and Increase the Efficiency of the Navy at the Close of the Present War?’, Proceedings 45:3:193 (1919)

Ferris, John R., ‘‘The Greatest Power on Earth’: Great Britain in the 1920s’, International History Review 13:4 (1991), pp. 726-750

Freedman, Lawrence, Strategy: A History (New York: Oxford University Press, 2013)

Halewood, Louis, ‘Internationalising Sea Power: Ideas of World Order and the Maintenance of Peace, 1890-1922’, (DPhil thesis, University of Oxford, 2020)

Hull, Isabel, A Scrap of Paper: Breaking and Making International Law during the Great War (Ithaca: Cornell University Press, 2014)

Kennedy, Paul, Strategy and Diplomacy, 1870-1945: Eight Studies (London: Allen & Unwin, 1983)

Lambert, Andrew, Seapower States: Maritime Culture, Continental Empires and the Conflict that Shaped the Modern World (New Haven: Yale University Press, 2018)

Mackinder, Halford J., Democratic Ideals and Reality: A Study in the Politics of Reconstruction (New York: Henry Holt and Company, 1919)

Mackinder, Halford J., ‘The Geographical Pivot of History’ in The Geographical Journal 170:4 (1904), pp. 421-437

MacMillan, Margaret, Peacemakers: The Paris Peace Conference of 1919 and Its Attempt to End War (London: John Murray, 2001)

Mahan, Alfred Thayer, The Influence of Sea Power Upon History, 1660-1783 (London: Sampson Low, Marston & Co., Ltd., 1980)

Mahan, Alfred Thayer, The Interest of America in Sea Power, Present and Future (Port Washington: Kennikat, 1897)

McCrae, Meighen, Coalition Strategy and the End of the First World War: The Supreme War Council and War Planning, 1917-1918 (Cambridge: Cambridge University Press, 2019)

Morgan-Owen, David, ‘War as It Might Have Been: British Sea Power and the First World War’, The Journal of Military History 83 (2019), pp. 1095-1131

Philpott, William, War of Attrition: Fighting the First World War (London: Little, Brown, 2014)

Sheffield, Gary, Forgotten Victory: The First World War: Myths and Realities (London: Headline, 2001)

Strachan, Hew, ‘Masters of the Seas: Naval Power and the First World War’, Rothermere American Institute (29th June 2016) 

Venier, Pascal, ‘La pensée géopolitique de Sir Halford Mackinder, l’apôtre de la puissance amphibie’, in Hevré Coutau-Bégarie and Martin Motte, Approaches de la géopolitique, de l’Antiquitié à nos jours (Paris: Economica, 2013), pp. 483-507