As soon as he arrived in Castille, Cabot received the rank of captain, by an edict dated the 20th of October, 1512, with a salary of 5000 maravédis. Seville was fixed upon for his residence, until an opportunity might arise of turning his talents and experience to account. There was a plan on foot for his taking the command of a very important expedition, when Ferdinand the Catholic died, on the 23rd of January, 1516. Cabot returned at once to England, having probably obtained leave of absence. Eden tells us that the following year Cabot was appointed with Sir Thomas Pert to the command of a fleet which was to reach China by the north-west. On the 11th of June, he was in Hudson's Bay at 67½° of latitude; the sea free from ice spread itself out before him so far that he reckoned upon success in his enterprise, when the faintheartedness of his companion, together with the cowardice and mutinous spirit of the crews, who refused to go any further, obliged him to return to England. In his Theatrum orbis terrarum, Ortelius traces the shape of Hudson's Bay as it really is; he even indicates at its northern extremity a strait leading northwards. How can the geographer have attained to such exactness? "Who," says Mr. Nicholls, "can have given him the information set forth in his map, if not Cabot?"

On his return to England, Cabot found the country ravaged by a horrible plague, which put a stop even to commercial transactions. Soon, either because the time of his leave had expired, or that he wished to escape from the pestilence, or that he was recalled to Spain, the Venetian navigator returned to that country. In 1518, on the 5th of February, Cabot was made pilot-major, with a salary which, added to that which he already had, made a total of 125,000 maravédis, say, 300 ducats. He did not actually exercise the functions of his office till Charles V. returned from England. His principal duty consisted in examining pilots, who were not allowed to go to the Indies until after having passed this examination.

This epoch was by no means favourable to great maritime expeditions. The struggle between France and Spain absorbed all the resources both in men and money, of these two countries—Cabot too, who seems to have adopted science for his fatherland, much more than any particular country, made some overtures to Contarini, the Ambassador of Venice, to take service on board the fleets of the Republic; but when the favourable answer of the Council of Ten arrived, he had other projects in his head, and did not carry his attempt any further.

Cabot presides over a Conference of Cosmographers.

In the month of April, 1524, Cabot presided at a conference of mariners and cosmographers, which met at Badajoz, to discuss the question whether the Moluccas belonged, according to the celebrated treaty of Tordesillas, to Spain or Portugal. On the 31st of May, it was decided that the Moluccas were within the Spanish waters, by 20°. Perhaps this resolution of the junta of which Cabot was president, and which again placed in the hands of Spain a great part of the spice trade, was not without its influence upon the resolutions of the council of the Indies. However this may be, in the month of September of the same year Cabot was authorized to take the command of three vessels of 100 tons, and a small caravel, carrying together 150 men, with the title of captain-general.

The declared aim of this voyage was to pass through the Strait of Magellan, carefully to explore the western coast of America, and to reach the Moluccas, where they would take in on their return a cargo of spices. The month of August, 1525, had been fixed upon as the date of departure, but the intrigues of Portugal succeeded in delaying it until April, 1526.

Different circumstances seem from this moment to have augured ill for the voyage. Cabot had only a nominal authority, and the association of merchants who had defrayed the expenses of the equipment not accepting him willingly as chief, had found means to oppose all the plans of the Venetian sailor. Thus it was that in place of the man whom he had appointed as second in command, another was imposed upon him, and that instructions destined to be unsealed when at sea were delivered to each captain. They contained this absurd arrangement, that in case of the death of the captain-general, eleven individuals were to succeed him each in his turn. Was not this an encouragement given to assassination?

Scarcely was the fleet out of sight of land, when discontent appeared. The rumour spread that the captain-general was not equal to his task; then as they saw that these calumnies did not affect him, they pretended that the flotilla was already short of provisions. The mutiny broke out as soon as land was reached, but Cabot was not the man to allow himself to be annihilated by it; he had suffered too much from Sir Thomas Pert's cowardice to bear such an insult. In order to nip the evil in the bud, he had the mutinous captains seized, and notwithstanding their reputation and the brilliancy of their past services, he made them get into a boat, and abandoned them on the shore. Four months afterwards they had the good luck to be picked up by a Portuguese expedition, which seems to have had orders to thwart the plans of Cabot.

The Venetian navigator then penetrated into the Rio de la Plata, the exploration of which had been commenced by his predecessor the Pilot-major de Solis. The expedition was not then composed of more than two vessels, one having been lost during the voyage. Cabot sailed up the Argent River, and discovered an island which he called Francis Gabriel, and upon which he built the fort of San Salvador, entrusting the command of it to Antonio de Grajeda. Cabot had the keel removed from one of his caravels, and with it, being towed by his small boats, entered the Parana, built a new fort at the confluence of the Carcarama and Terceiro, and after having thus secured his line of retreat he pursued the course of these rivers farther into the interior. Arriving at the confluence of the Parana and Paraguay, he followed the second, the direction of which agreed best with his project of reaching the region of the west where silver was to be obtained. But it was not long before the aspect of the country changed, and the attitude of the inhabitants altered also. Until now, they had collected in crowds, astonished at the sight of the vessels; but upon the cultivated shores of the Paraguay they courageously opposed the strangers' landing, and three Spaniards having tried to knock down the fruit from a palm-tree, a struggle took place, in which 300 natives lost their lives. This victory had disabled twenty-five Spaniards. It was too much for Cabot, who rapidly removed his wounded to the fort San Spirito and retired, still presenting a bold front to the enemy.

Cabot had already sent two of his companions to the Emperor, to acquaint him with the attempt at revolt of the captains, to explain to him the motives which obliged him to modify the course marked out for his voyage, and to request aid from him, both in men and provisions. The answer arrived at last. The Emperor approved of what Cabot had done, and ordered him to colonize the country in which he had just made a settlement, but did not send him either one man or a single maravédi. Cabot tried to procure the resources which he needed in the country, and caused some attempts at cultivation to be commenced. At the same time, to keep his troops in exercise, he reduced the neighbouring nations to obedience, had some forts built, and again sailing up the Paraguay he reached Potosi, and the water-courses of the Andes which feed the basin of the Atlantic. At last he prepared to enter Peru, from whence came the gold and silver which he had seen in the possession of the natives; but it needed more troops than he could muster, to attempt the conquest of this vast region. The Emperor, however, was quite unable to send him any. His European wars absorbed all his resources, the Cortez refused to vote new subsidies and the Moluccas had just been pledged to Portugal. In this state of affairs, after having occupied the country for five years, and waited all this time for the assistance which never came, Cabot decided to evacuate a part of his settlements, and he returned with some of his people to Spain. The rest, amounting to 120, men who were left to guard the fort of San Spirito, after many vicissitudes which cannot be related here, perished by the hands of the Indians, or were obliged to take refuge in the Portuguese settlements on the coast of Brazil. It is to the horses imported by Cabot that is due the wonderful race of wild horses which may be seen in large troops on the pampas of La Plata at the present day; this was the only result of the expedition.