Sea power, classically defined as a strategy to control communications, was an essential asset for the creation of European maritime empires, enabling them to secure seaborne trade, open new markets, and acquire territory. It has often been conflated with seapower, a concept developed by the ancient Athenians to distinguish states like their own, whose economy, culture, and identity were enmeshed in the maritime sphere, from continental military powers like Sparta and Persia. In this period Britain, the only seapower Great Power, created an extensive maritime empire outside Europe, one combining colonies of settlement, like Australia, with those of occupation, and informal imperialism based on economic power. While many Continental European powers created maritime empires after 1815, they did so in the knowledge that their possessions would be exposed to British naval power in the event of war, and tended to focus on land and security rather than commerce.

The maritime aspects of the wars of the French Revolution and Empire were asymmetric, between a British seapower empire of oceanic connectivity and a French dominated European system that focussed on territorial control and economic restriction. The inclusive British political system privileged naval strength, the defence of trade, and sea control. This position was based on battle fleet dominance, which remained undefeated across two decades. British identity became ever more closely linked to naval success as Nelson, the Nile and Trafalgar added new names to national culture. This sustained long-term funding for major infrastructure projects, new ships, and high levels of skilled manpower. Superior ships and men enabled the Royal Navy to defeat naval rivals, and attacks on commercial shipping by national warships and privateers. Naval dominance sustained a hard-line economic war that broke the Russian economy, and seriously damaged that of France, while the City of London and the British economy more generally continued to support the national war effort through extensive capital loans, and private measures, such as those of Lloyds Patriotic Fund. Seapower could not defeat Napoleon, it supported a grand alliance that would achieve that aim. By 1815 Britain had become a global seapower empire of unrivalled wealth and influence.