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.

Often depicted by historians as a ‘forgotten’ war in the United States and unwanted distraction for Britain and its empire (with the exception of Canada), the Anglo-American War of 1812 for contemporaries was a conflict with high states. For the divided United States, the war was fought for a myriad of reasons, including outrage over British impressment of American sailors and infringements free trade, fear of American Indians, and a desire to re-assert American independence and lay claim to the position of pre-eminent power in North America. While victory offered tangible and moral prizes, defeat risked the shattering of the already-frail political unity of the young republic and relegation to secondary status in North America. For the British Empire, the war meant conflict with its primary overseas trading partner, which risked economic ruin for its manufacturing and shipping industries and resulted in severe opposition in some parts of the country. Victory, however, presented the tantalizing opportunity to avenge the embarrassment of the American Revolution and reaffix the young republic to the British sphere of influence. While the conflict itself resulted in few casualties and a treaty that recognized no victor, it ultimately shaped the future of North America and the direction of the British Empire.

Presidents Jefferson and Madison’s Republican-backed policies prompted new waves of state interposition. Federalist-dominated state legislatures in New England passed interposition resolutions that protested:Jefferson’s Embargo Acts (1807–1809); United States v. Peters (1809) emphasizing the Supreme Court’s finality over constitutionality; the recharter of the Bank of the United States; and Madison’s efforts to mobilize state militias before the War of 1812. After the controversy over the Alien and Sedition Acts and Jefferson’s election in 1800, Americans might have expected Republicans to advocate strict construction of national powers under the Constitution while Federalists would urge broader powers. However, defenses of states’ rights never belonged exclusively to one political viewpoint or party. Americans debated whether sounding the alarm resolutions and state interposition were legitimate state actions – and some asked if and when they would be justified in more forcefully resisting federal law, notably during the Hartford Convention in 1814 that called for constitutional amendments to reduce the power of Southern states and the repeal of the Three-Fifths Clause.

This chapter opens the first part of the book that presents the background of the First World War. It deals with the emergence of the concept of “enemy alien” in the debate among international lawyers. Starting with the Law of Nations published by Emer de Vattel in 1758, it analyzes and discusses what the foundational texts of international law in the century-and-a-half preceding the First World War said on the rights of foreigners in peacetime and on the conduct toward these same foreigners when they became enemies in wartime. It then compares legal doctrines and practices analyzing the behavior of belligerents towards enemy aliens in a string of interstate wars that occurred between the end of the eighteenth century and 1865, namely the French Revolutionary Wars of 1792–1793, the Napoleonic Wars, the War of 1812 between Britain and the United States, the Crimean War and the American Civil War. The chapter follows the changes in the attitude toward enemy aliens that mass conscription and the post-French Revolution concept of citizenship and nationality triggered.