The explorer De Soto sailed for Florida in 1539, in search of gold. He had in his command five hundred and thirteen men, exclusive of sailors, and two hundred and thirty-seven horses, besides some for the purpose of bearing burdens, the number not given. In all his weary journey of three years he found the Indians active, hostile, and courageous fighters. In one of his first battles he lost twelve horses, and had seventy wounded. He pursued many phantoms in search of gold, in different directions, but his general course was westward and northwestward. He was the first European to discover the Mississippi River, not far from the mouth of the Arkansas, and there he was buried in the middle of the river, to prevent the Indians from discovering he was dead and from desecrating his remains. His followers then determined to push on westward to Mexico, and reached as far as the borders of Texas, probably, when they became discouraged with the magnitude of the difficulties that surrounded them, and determined to return and seek an outlet from the wilderness by water. On this last journey, west of the Mississippi, they suffered their greatest loss of horses. They had not been shod for more than a year, and a great many were lame and unable to travel. When the Spaniards had completed their boats and were ready to leave the scenes of their sufferings and disasters, they turned loose upon the bank of the river their four or five remaining horses, which manifested great excitement, running up and down the bank neighing for their masters, as they sailed away. This alarmed the Indians and they ran into the water for safety.
The Indians were afraid of the horses and the horses were afraid of the Indians. It seems to be a fact, observed in all the early intercourse of the Spaniards with the Indians, that universally they had a kind of superstitious awe of the horse as a superior being, and it is probably due to this awe that the Indians did not utterly destroy every horse that fell out of the ranks or that escaped in the wilderness. As I understand the history of this terrible exploration, when the Spaniards crossed the Mississippi they had two hundred and fifty men and one hundred and fifty horses, and when they came back and were ready to sail they had but four or five horses left. It is fair, therefore, to conclude that the greater portion of these hundred and fifty head was scattered in the wilderness as they went out and as they returned. This provides a sufficient breeding basis for the countless multitudes of descendants, and places that nucleus in the right region to nourish them in a feral state.