This “Rhea letter” became the innocent source of one of the most famous controversies in American history.  Jackson supposed that the communication had been promptly delivered to Monroe, and that his plan for the conquest of Florida had the full, if secret, approval of the Administration.  Instructions from the Secretary of War, Calhoun, seemed susceptible of no other interpretation; besides, the conqueror subsequently maintained that he received through Rhea the assurance that he coveted.  Monroe, however, later denied flatly that he had given any orders of the kind.  Indeed he said that through a peculiar combination of circumstances he had not even read Jackson’s letter until long after the Florida campaign was ended.  Each man, no doubt, thought he was telling the truth, and historians will probably always differ upon the merits of the case.  The one thing that is perfectly certain is that Jackson, when he carried his troops into Florida in 1818, believed that the Government expected him to prepare the territory for permanent American occupation.

In early March, Jackson was at Fort Scott, on the Georgia frontier, with about two thousand men.  Though he expected other forces, Jackson found that scarcity of rations made it inadvisable to wait for them, and he therefore marched his army on as rapidly as possible down the soggy bank of the Apalachicola, past the ruins of Negro Fort, into Florida, where he found in readiness the provisions which had been sent forward by way of Mobile.  Turning eastward, Jackson bore down upon the Spanish settlement of St. Marks, where it was rumored that the hostile natives had assembled in considerable numbers.  A small fleet of gunboats from Mobile and New Orleans was ordered to move along the coast and intercept any fugitives, “white, red, or black.”  Upwards of two thousand friendly Indians joined the land expedition, and the invasion became from a military standpoint a sheer farce.  The Seminoles were utterly unprepared for war, and their villages were taken possession of, one by one, without opposition.  At St. Marks the Indians fled precipitately, and the little Spanish garrison, after a glimpse of the investing force, asked only that receipts be given for the movable property confiscated.  The Seminole War was over almost before it was begun.

But Jackson was not in Florida simply to quell the Seminoles.  He was there to vindicate the honor and establish the sovereignty of the United States.  Hence there was further work for him to do.  The British instigators of lawlessness were to be apprehended; the surviving evidences of Spanish authority were to be obliterated.  Both objects Jackson attained with characteristic speed and thoroughness.  At St. Marks he made Arbuthnot a prisoner; at Suwanee he captured another meddler by the name of Ambrister; and after a court-martial he hanged one and shot the other in the presence of the chieftains whom these men had deceived into thinking that Great Britain stood ready to come to the red man’s relief.  Two Indian chiefs who were considered ringleaders he likewise executed.  Then, leaving St. Marks in the possession of two hundred troops, Jackson advanced upon Pensacola, the main seat of Spanish authority in the colony.