During the Canadian rebellion of 1837 Americans along the border expressed openly their sympathy for the insurgents who secured arms and munitions from the American side. In December a British force crossed the Niagara River, boarded and took possession of the Caroline, a vessel which had been hired by the insurgents to convey their cannon and other supplies. The ship was fired and sent over the Falls. When the Caroline was boarded one American, Amos Durfee, was killed and several others wounded. The United States at once demanded redress, but the British Government took the position that the seizure of the Caroline was a justifiable act of self-defense against people whom their own government either could not or would not control.
The demands of the United States were still unredressed when in 1840 a Canadian named Alexander McLeod made the boast in a tavern on the American side that he had slain Durfee. He was taken at his word, examined before a magistrate, and committed to jail in Lockport. McLeod's arrest created great excitement on both sides of the border. The British minister at Washington called upon the Government of the United States "to take prompt and effectual steps for the liberation of Mr. McLeod." Secretary of State Forsyth replied that the offense with which McLeod was charged had been committed within the State of New York; that the jurisdiction of each State of the United States was, within its proper sphere, perfectly independent of the Federal Government; that the latter could not interfere. The date set for the trial of McLeod was the fourth Monday in March, 1841. Van Buren's term ended and Harrison's began on the 4th of March, and Webster became Secretary of State. The British minister was given instructions by his government to demand the immediate release of McLeod. This demand was made, he said, because the attack on the Caroline was an act of a public character; because it was a justifiable use of force for the defense of British territory against unprovoked attack by "British rebels and American pirates"; because it was contrary to the principles of civilized nations to hold individuals responsible for acts done by order of the constituted authorities of the State; and because Her Majesty's government could not admit the doctrine that the Federal Government had no power to interfere and that the decision must rest with the State of New York. The relations of foreign powers were with the Federal Government. To admit that the Federal Government had no control over a State would lead to the dissolution of the Union so far as foreign powers were concerned, and to the accrediting of foreign diplomatic agents, not to the Federal Government, but to each separate State. Webster received the note quietly and sent the attorney-general to Lockport to see that McLeod had competent counsel. After considerable delay, during which Webster replied to the main arguments of the British note, McLeod was acquitted and released.
In the midst of the dispute over the case of the Caroline serious trouble arose between the authorities of Maine and New Brunswick over the undetermined boundary between the St. Croix River and the Highlands, and there ensued the so-called "Aroostook War." During the summer of 1838 British and American lumbermen began operating along the Aroostook River in large numbers. The governor of Maine sent a body of militia to enforce the authority of that State, and the New Brunswick authorities procured a detachment of British regulars to back up their position. Bloodshed was averted by the arrival of General Winfield Scott, who managed to restrain the Maine authorities. The administration found it necessary to take up seriously the settlement of the boundary question, and for the next three years the matter was under consideration, while each side had surveyors employed in a vain attempt to locate a line which would correspond to the line of the treaty. As soon as the McLeod affair was settled, Webster devoted himself earnestly to the boundary question. He decided to drop the mass of data accumulated by the surveyors and historians, and to reach an agreement by direct negotiation.
In April, 1842, Alexander Baring, Lord Ashburton, arrived in Washington and the following August the Webster-Ashburton treaty was signed. The boundary fixed by the treaty gave Maine a little more than half the area which she claimed and the United States appropriated $150,000 to compensate Maine for the territory which she had lost.
The settlement of these matters did not, however, insure peace with England. Settlers were crowding into Oregon and it was evident that the joint occupation, established by the convention of 1818, would soon have to be terminated and a divisional line agreed upon. Great Britain insisted that her southern boundary should extend at least as far as the Columbia River, while Americans finally claimed the whole of the disputed area, and one of the slogans of the presidential campaign of 1844 was "Fifty-Four-Forty or Fight." At the same time Great Britain actively opposed the annexation of Texas by the United States. Her main reason for this course was that she wished to encourage the development of Texas as a cotton-growing country from which she could draw a large enough supply to make her independent of the United States. If Texas should thus devote herself to the production of cotton as her chief export crop, she would, of course, adopt a free-trade policy and thus create a considerable market for British goods.
As soon as it became evident that Tyler contemplated taking definite steps toward annexation, Lord Aberdeen secured the coöperation of the government of Louis Philippe in opposing the absorption of Texas by the American republic. While the treaty for the annexation of Texas was before the Senate, Lord Aberdeen came forward with a proposition that England and France should unite with Texas and Mexico in a diplomatic act or perpetual treaty, securing to Texas recognition as an independent republic, but preventing her from ever acquiring territory beyond the Rio Grande or joining the American union. While the United States would be invited to join in this act, it was not expected that the government of that country would agree to it. Mexico obstinately refused to recognize the independence of Texas. Lord Aberdeen was so anxious to prevent the annexation of Texas that he was ready, if supported by France, to coerce Mexico and fight the United States, but the French Government was not willing to go this far, so the scheme was abandoned.
The two foremost issues in the campaign of 1844 were the annexation of Texas and the occupation of Oregon. Texas was annexed by joint resolution a few days before the inauguration of Polk. This act, it was foreseen, would probably provoke a war with Mexico, so Polk's first task was to adjust the Oregon dispute in order to avoid complications with England. The fate of California was also involved. That province was not likely to remain long in the hands of a weak power like Mexico. In fact, British consular agents and naval officers had for several years been urging upon their government the great value of Upper California. Aberdeen refused to countenance any insurrectionary movement in California, but he directed his agents to keep vigilant watch on the proceedings of citizens of the United States in that province. Had England and Mexico arrived at an understanding and joined in a war against the United States, the probabilities are that England would have acquired not only the whole of Oregon, but California besides. In fact, in May, 1846, just as we were on the point of going to war with Mexico, the president of Mexico officially proposed to transfer California to England as security for a loan. Fortunately, the Oregon question had been adjusted and England had no reason for wishing to go to war with the United States. Mexico's offer was therefore rejected. Polk managed the diplomatic situation with admirable promptness and firmness. Notwithstanding the fact that the democratic platform had demanded "Fifty-Four-Forty or Fight," as soon as Polk became President he offered to compromise with England on the 49th parallel. When this offer was declined he asked permission of Congress to give England the necessary notice for the termination of the joint occupation agreement, to provide for the military defense of the territory in dispute, and to extend over it the laws of the United States. A few months later notice was given to England, but at the same time the hope was expressed that the matter might be adjusted diplomatically. As soon as it was evident that the United States was in earnest, England gracefully yielded and accepted the terms which had been first proposed.
As war with Mexico was imminent the public generally approved of the Oregon compromise, though the criticism was made by some in the North that the South, having secured in Texas a large addition to slave territory, was indifferent about the expansion of free territory. In fact, Henry Cabot Lodge, in his recent little book, "One Hundred Years of Peace," says: "The loss of the region between the forty-ninth parallel and the line of 54-40 was one of the most severe which ever befell the United States. Whether it could have been obtained without a war is probably doubtful, but it never ought to have been said, officially or otherwise, that we would fight for 54-40 unless we were fully prepared to do so. If we had stood firm for the line of 54-40 without threats, it is quite possible that we might have succeeded in the end; but the hypotheses of history are of little practical value, and the fact remains that by the treaty of 1846 we lost a complete control of the Pacific coast."
That the United States lived through what Professor Dunning calls "the roaring forties" without a war with England seems now little less than a miracle. During the next fifteen years relations were much more amicable, though by no means free from disputes. The most important diplomatic act was the signature in 1850 of the Clayton-Bulwer treaty which conceded to England a joint interest in any canal that might be built through the isthmus connecting North and South America. One of the interesting episodes of this period was the dismissal of Crampton, the British minister, who insisted on enlisting men in the United States for service in the Crimean War, an act which pales into insignificance in comparison with some of the things which Bernstorff did during the early stages of the Great War.
Relations between the United States and England during the American Civil War involved so many highly technical questions that it is impossible to do more than touch upon them in the present connection. Diplomatic discussions centred about such questions as the validity of the blockade established by President Lincoln, the recognition by England of Confederate belligerency, the Trent affair, and the responsibility of England for the depredations committed by the Alabama and other Confederate cruisers. When the United States first demanded reparation for the damage inflicted on American commerce by the Confederate cruisers, the British Government disclaimed all liability on the ground that the fitting out of the cruisers had not been completed within British jurisdiction. Even after the close of the war the British Government continued to reject all proposals for a settlement. The American nation, flushed with victory, was bent on redress, and so deep-seated was the resentment against England, that the Fenian movement, which had for its object the establishment of an independent republic in Ireland, met with open encouragement in this country. The House of Representatives went so far as to repeal the law forbidding Americans to fit out ships for belligerents, but the Senate failed to concur. The successful war waged by Prussia against Austria in 1866 disturbed the European balance, and rumblings of the approaching Franco-Prussian war caused uneasiness in British cabinet circles. Fearing that if Great Britain were drawn into the conflict the American people might take a sweet revenge by fitting out "Alabamas" for her enemies, the British Government assumed a more conciliatory attitude, and in January, 1869, Lord Clarendon signed with Reverdy Johnson a convention providing for the submission to a mixed commission of all claims which had arisen since 1853. Though the convention included, it did not specifically mention, the Alabama Claims, and it failed to contain any expression of regret for the course pursued by the British Government during the war. The Senate, therefore, refused by an almost unanimous vote to ratify the arrangement.