BOOK ONE - CHAPTER THREE
28 June 2026
From Continental Republic to Maritime Superpower
How the United States Changed Its Grand Strategy
Why would a country that spent a century fighting for land suddenly decide the ocean mattered more?
From Coast to Coast to Command of the Seas
Fast-track overview (30 second read)
The United States began as a continental power, expanding across North America through purchase, diplomacy and war. Once it reached the Pacific, land conquest stopped paying off - so it pivoted to trade, and trade needed a navy. That pivot, shaped by thinkers like Alfred Thayer Mahan, turned a continental republic into the world's dominant maritime power.
The United States did not begin life as a maritime power. For much of the nineteenth century, it behaved like a classic continental state, expanding across North America through diplomacy, purchase and war. Only later did it adopt the maritime strategy that would make it the world's leading global power. This chapter based on lectures given by Sarah Paine traces that shift - and why it matters for understanding American strategy today.
Contents cover the following:
1. America Begins as a Continental Power
2. Expansion Across a Continent
3. The Monroe Doctrine
4. Reaching the Pacific Changes Everything
5. The Great Strategic Transformation
6. Lessons from America's Evolution
Why it matters
Understanding this shift explains why the United States still organises its power around naval dominance and open sea lanes rather than territorial control - a strategic instinct with roots stretching back over a century, and one still shaping today's great power competition.
1. America Begins as a Continental Power
When the United States declared independence in 1776, its principal concern was not overseas trade or global influence. It was survival.
The young republic occupied a narrow strip along the Atlantic coast. To the west lay vast territories controlled by Native American nations, France and Spain. To the north stood British Canada, while the Gulf of Mexico remained under foreign control.
Like other continental powers, the United States viewed territorial expansion as the path to security and prosperity. Its strategic objective was straightforward: reach the Pacific Ocean.
Glossary
Continental power - a state whose security depends primarily upon controlling and defending land territory.
Territorial expansion - the acquisition of additional land through purchase, settlement, diplomacy or conquest.
2. Expansion Across a Continent
Sarah Paine points out that America expanded differently from many earlier continental empires. Whenever possible, it preferred diplomacy and financial negotiation over military conquest.
- The Louisiana Purchase (1803) from France doubled the country's size.
- The Adams-Onis Treaty (1819) secured Florida from Spain.
- The Alaska Purchase (1867) transferred Russian America to the United States.
When negotiation failed, however, force followed. The Mexican-American War (1846-1848) resulted in the annexation of vast territories including present-day California, Nevada, Utah and much of Arizona and New Mexico.
Paine notes that even the United States, often viewed today as a maritime power, spent much of its early history behaving like a continental state.
Glossary
Manifest Destiny - the nineteenth-century belief that the United States was destined to expand across North America.
Checkbook diplomacy - achieving strategic objectives through financial agreements rather than military force.
3. The Monroe Doctrine
In 1823, President James Monroe announced what became known as the Monroe Doctrine. European powers were warned against establishing new colonies or interfering in the affairs of the Western Hemisphere.
In practice, the United States lacked the military strength to enforce this declaration. The British Royal Navy largely upheld it because Britain also wished to prevent rival European empires from re-establishing colonial monopolies in the Americas.
Even so, the Monroe Doctrine illustrates continental thinking. It asserted an exclusive sphere of influence rather than promoting an open international order.
Glossary
Sphere of influence - a region in which one great power claims predominant political or strategic influence.
Open international order - a system of international relations based on agreed rules, open trade, freedom of navigation and respect for national sovereignty. Supporters argue it promotes growth and reduces conflict; critics contend it can reflect the interests of the most powerful states.
Monroe Doctrine - an American foreign policy declaration issued in 1823 opposing further European colonial expansion in the Americas.
4. Reaching the Pacific Changes Everything
By the late nineteenth century, the United States had achieved what earlier generations sought: it stretched from the Atlantic to the Pacific, and its continental frontier was largely complete.
This transformed America's strategic position. No longer focused solely on acquiring territory, it could increasingly turn towards overseas commerce. Industrialisation generated enormous productive capacity; factories required export markets, and imports became equally important. Trade replaced land acquisition as the principal engine of national wealth.
This was precisely the environment in which Alfred Thayer Mahan's ideas gained influence. He argued that national greatness depended not upon conquering more territory but upon protecting maritime trade through naval power. His ideas profoundly influenced American policymakers.
Glossary
Industrialisation - the transition from an agricultural economy to one based upon manufacturing and industry.
Naval power - the ability to protect commerce and project national influence through maritime forces.
5. The Great Strategic Transformation
Sarah Paine argues that this marked one of the most important shifts in American history. The United States did not abandon its continental foundations. Rather, it added a maritime dimension to its strategy.
Its geography now offered exceptional advantages: two great oceans protected its flanks, abundant natural resources supported industry, navigable rivers connected the interior, and expanding ports linked America to global markets.
Few countries possessed such a favourable combination of continental resources and maritime access. During the twentieth century these advantages enabled the United States to emerge as the world's foremost maritime power while retaining the industrial strength of a continental economy.
Glossary
Grand strategy - the long-term coordination of diplomatic, military, economic and political power to achieve national objectives.
Maritime strategy - a strategy centred upon naval strength, overseas commerce and secure sea communications.
6. Lessons from America's Evolution
Paine's historical survey illustrates an important principle. Geography provides opportunities, but it takes strategy for nations to exploit them.
America's rise was not inevitable. Its leaders gradually recognised that once continental expansion had been completed, future prosperity depended less upon acquiring additional land and more upon protecting international trade, maintaining secure sea lanes and building alliances.
This transformation laid the foundations for the modern international order that emerged after the Second World War. In the next chapter we examine the thinker who explained why this maritime transformation mattered so profoundly: Admiral Alfred Thayer Mahan.
Bottom Line
The United States began as a continental republic. During the nineteenth century it expanded across North America through diplomacy, purchase and war. Once that expansion ended, its strategic outlook changed fundamentally - from security through territory to prosperity through commerce and security through command of the seas.
What is original here is the framing: America's maritime rise is often told as destiny, but Paine's account - and this chapter's - shows it as a pivot, a strategic choice made only once continental options were exhausted. That reframing matters for how we read rising powers today, including those still in their continental phase.
Next in the series: the man whose ideas gave this pivot its intellectual foundation - Alfred Thayer Mahan.
Test Me
- If America's continental frontier had not closed when it did, do you think the maritime pivot would have happened at all - or happened differently?
- Britain enforced the Monroe Doctrine for its own reasons, not America's. Where else in history has one power's strategy been upheld by another power's self-interest?
- Paine frames geography as opportunity, not destiny. What other nation today sits on geographic advantages it has not yet turned into strategy?
Related Articles
Parts 1 and 2 in this series are already published:
Part 1: Continental and Maritime Powers
Part 2: Thinkers Who Changed How We See Power
Parts 4, 5 and 6 are in publication.
Further Reading
Max Otte:
https://youtu.be/riz5hs2fkGo?is=qaPwqMYrdY54RiIC
https://youtu.be/tJWqn9I4sYU?is=0Dr04kIUNg9H-0ta
https://youtu.be/HC3RIAVQ9dY?is=WP737dyTJoZR9rpU
Sarah Paine - playlist:
https://youtube.com/playlist?list=PLd7-bHaQwnthnOed1a85mF7L-Ki3kdiqp&si=nulceh38zApV0n8v
References
Sarah C. M. Paine, The Strategy of Strategy: Rethinking War and Peace.
Alfred Thayer Mahan, The Influence of Sea Power upon History (1890).
James Monroe, Seventh Annual Message to Congress (Monroe Doctrine), 2 December 1823.
Walter A. McDougall, Promised Land, Crusader State (1997).











