On October 20, 1818, Benjamin Rush and Albert Gallatin, ministers to England and France respectively, concluded a convention with Great Britain which left the fate of the Oregon country in suspense for a period of ten years. To the British claims of prior discovery by Cook and Mackenzie and of prior occupation by the Hudson's Bay Company, the American commissioners opposed the claims based on the voyage of Captain Gray in 1792 and on the founding of Astoria by John Jacob Astor in 1811. It was finally agreed that the northern boundary of the United States should run from the Lake of the Woods to the Stony Mountains, along the forty-ninth parallel, and that the disputed country beyond the mountains should be occupied jointly for a period of ten years. An agreement was also reached regarding the Newfoundland and Labrador fisheries.
On another frontier conditions existed to which Congress could not remain indifferent. East Florida was still a thorn in the side of Georgia and Alabama. The province had become a rendezvous for pirates, filibusters, renegade Indians, and runaway negroes. Creek warriors who would not submit to the loss of their lands had taken refuge with their kinsmen, the Seminoles, and were inciting malcontents of every stripe against the whites. A band of negroes, estimated at not less than a thousand in number, together with some Creek Indians, had taken possession of an abandoned fort on the Apalachicola and had terrorized the country for miles around. The Spanish commander at Pensacola was summoned to destroy this pirates' nest and to disperse the marauders; but he was either unable or unwilling to do so, and in 1816 a red-hot shot from a United States gunboat blew up the magazine of the negro fort, killing nearly three hundred men, women, and children. Early in 1818, in equally summary fashion troops of the United States expelled a band of freebooters from Amelia Island.
The slight regard which the United States paid to the territorial sovereignty of Spain in Florida sprang from a general conviction that Spain could not and would not observe the provisions of the Treaty of 1795. Spain had then agreed to restrain the Indians living within her borders from attacking the citizens or Indians of the United States. President Monroe seemed to assume that Spain had forfeited her rights over Florida. At all events, he authorized General Andrew Jackson to assume command of the forces at Fort Scott and to call on the governors of adjacent States for militia to terminate the war. This order of December 26, 1817, was stated in dangerously broad terms. Jackson did not doubt for an instant that it authorized him to pursue the Indians into Florida. To his mind the time seemed opportune for the seizure of East Florida as an indemnity for the outrages committed by the Seminoles. He wrote to the President to this effect. "Let it be signified to me," said he, "through any channel (say Mr. J. Rhea) that the possession of the Floridas would be desirable to the United States and in sixty days it will be accomplished."
To his dying day Jackson maintained that the President signified his approval through Congressman Rhea, of Tennessee. Monroe denied that he had read Jackson's letter until after the exploits which so nearly plunged the country into war with Spain. Whatever may be the truth of the matter, General Jackson acted in accord with what he believed to be the President's desires. With a thousand men he marched across the border and was soon in possession of St. Mark's. Among those who fell into his hands was Alexander Arbuthnot, a Scotch trader who was suspected of inciting the Indians. Continuing his march, Jackson surprised and captured Suwanee, another rendezvous of Indians and runaway negroes. Here he found Robert Ambrister, another British subject, who was also regarded as a suspicious character. Returning to St. Mark's, Jackson handed these two suspects over to a court martial, which found both guilty of giving aid and comfort to the enemy and of inciting or waging war against the United States. Arbuthnot was hanged from the yardarm of his own schooner; Ambrister was shot. The fall of Pensacola finished the campaign. By the end of May, 1818, Florida was in the possession of the troops of the United States and Jackson was on his way to Tennessee, the idol of his men and a national hero in the estimation of the people of the Southwest.
The outcome of these exploits might easily have been war with both Spain and Great Britain. Don Luis de Onis, the Spanish Minister at Washington, immediately suspended the negotiations then in progress respecting the Floridas and made a spirited protest "against these acts of hostility and invasion." He demanded the immediate restitution of the places which had been seized, indemnity for all damage to property, and the punishment of General Jackson. As for Great Britain, Lord Castlereagh afterward said that, such was the temper of Parliament and the country, war might have been produced by holding up a finger and an address to the Crown carried by an almost unanimous vote.
The Cabinet of President Monroe was divided over the course to be pursued. Calhoun insisted that Jackson had virtually committed an act of war, which should be promptly disavowed. But Adams held—and the President was inclined to side with him—that in reality Spain had been the aggressor, and that Jackson had not violated the spirit of his orders. In order to terminate the war, Jackson had been obliged to cross the Spanish line. He had not done so with the purpose of waging war upon Spain.
Following a memorandum made by the President, Adams replied to Don Onis in this spirit. Later, in a masterly state paper, he set forth the intolerable conditions which obtained on the Florida frontier. The lax conduct of the Spanish authorities was held to justify the aggressive measures of Jackson. The United States was prepared to restore Pensacola and St. Mark's whenever Spain should give guaranties for the observance of treaty obligations. So far from consenting to punish Jackson, the United States demanded the punishment of those Spanish officials who had so flagrantly violated the obligations of the Treaty of 1795. "Spain must immediately make her election either to place a force in Florida at once adequate for the protection of her territory and to the fulfillment of her engagements, or cede to the United States a province of which she retains nothing but the nominal possession." This latter alternative, indeed, the Administration never lost from view.
Confronted by the revolt of all her American colonies, Spain could hardly resist this insistent pressure upon a province which she could neither govern nor defend. On February 22, 1819, Don Onis set his hand to a treaty which ceded the Floridas in return for the assumption by the United States of claims of American citizens against her to an amount not exceeding $5,000,000. The treaty contained also a definition of the boundary between Spanish and American possessions on the North American continent. Beginning at the mouth of the Sabine River, the line ran along that river to the thirty-second parallel; thence due north to the Red River, which it followed to the hundredth meridian; thence north to the Arkansas and along that river to its source; thence to the forty-second parallel, which it followed to the Pacific. As the United States renounced all claims to the west and south of this boundary, so Spain surrendered whatever shadowy title she had to the Northwest.