|“||The steamboat Caroline was a hostile vessel engaged in piratical war against her Majesty's people...it was under such circumstances, which it is to be hoped will never recur, that the vessel was attacked by a party of her Majesty's people, captured and destroyed.||”|
A group of Canadian rebels, led by William Lyon Mackenzie, seeking a Canadian republic, had been forced to flee to the United States after leading the failed Upper Canada Rebellion in Upper Canada (now Ontario). They took refuge on Navy Island on the Canadian side of the Niagara River, which separates the two countries (between Ontario and New York) and declared themselves the Republic of Canada under MacKenzie's "general" Rensselaer Van Rensselaer (nephew of General Stephen Van Rensselaer). American sympathizers supplied them with money, provisions, and arms via the steamboat SS Caroline.
On December 29, Canadian loyalist Colonel Sir Allan MacNab and Captain Andrew Drew of the Royal Navy commanding a party of militia, acting on information and guidance from Alexander McLeod that the vessel belonged to Mackenzie, crossed the international boundary and seized the Caroline, chased off the crew, towed her into the current, set her afire, and cast her adrift over Niagara Falls, after killing one black American named Amos Durfee in the process. His body was later exhibited in front of a recruiting tavern in Buffalo, New York.
|“||Those of our fellow citizens...single-handed and alone, left our territory and united themselves with a foreign power, have violated no law...they have done no more than has been done again and again by the people of every nation. Your own recollections of history will furnish your minds with hundreds of examples. The Swiss nation have, for hundreds of years, fed all the armies of Europe; and who ever though of holding them responsible for it? They did no more than Admiral Lord Cochrane did in taking part with South America. They did no more than Lord Byron did, who gave his life to aid the Greeks in breaking the chains of Turkish bondage. They did no more than Lafayette. Gentlemen, I am not deviating from the case further than is necessary to remove the just odium which has been unjustly thrown upon those who joined the insurgents.||”|
—Willis Hall, Attorney General in 1841 on the Caroline Affair.
US newspapers falsely reported "the death of twenty-two of her crew" when in fact, only Durfee was killed. Public opinion across the United States was outraged against the British. President Martin Van Buren protested strongly to London, but was ignored.
On May 29, 1838, 13 raiders, mostly Canadian refugees from the 1837 rebellion, led by William "Pirate Bill" Johnston, retaliated by capturing, looting, and burning the British steamer Sir Robert Peel while she was in U.S. waters. President Martin Van Buren sent General Winfield Scott to prevent further American incursions into Canada. However, there were several other attacks, the biggest being the Battle of the Windmill in November 1838.
The case was finally disposed of by U.S. Secretary of State Daniel Webster and Alexander Baring, 1st Baron Ashburton, in the course of their negotiations leading to the Webster–Ashburton Treaty of 1842. Secretary Webster admitted that the employment of force might have been justified by the necessity of self-defence, but denied that such necessity existed, while Lord Ashburton, although he maintained that the circumstances afforded excuse for what was done, apologized for the invasion of United States territory.
This incident has been used to establish the principle of "anticipatory self-defense" in international politics, which holds that it may be justified only in cases in which the "necessity of that self-defense is instant, overwhelming, and leaving no choice of means, and no moment for deliberation". This formulation is part of the Caroline test. The Caroline affair is also now invoked frequently in the course of the dispute around preemptive strike (or preemption doctrine).
- Searching for a Pirate's Lost Lair. By Shaun J. McLaughlin. Thousand Islands Magazine, February 13, 2012.
- Bassett Moore, John; Wharton, Francis e.a. (1906). A Digest of International Law. Volume 2. Government Printing Office. pp. 25, 409 & 410. Retrieved 2009-11-11.
- Howard Jones; To the Webster-Ashburton Treaty: A Study in Anglo-American Relations, 1783-1843 University of North Carolina Press, 1977
- Kenneth R. Stevens; Border Diplomacy- The Caroline and McLeod Affairs in Anglo-American-Canadian Relations, 1837-1842 University of Alabama Press, 1989; ISBN 0-8173-0434-7
- Wood, Christopher. The Caroline, Max Planck Encyclopedia of Public International Law
- The Caroline Case : Anticipatory Self-Defence in Contemporary International Law
- The Caroline Incident during the Patriot War
- Obituary of Neil MacGregor, one of the Upper Canada militiamen on the raid
- The Avalon Project at Yale Law School: The Webster-Ashburton Treaty and The Caroline Case
- Chapter 7, "British Steamer is Burned by Patriots" in Northern New York In The Patriot War, 1923, By L. N. Fuller