The relations between the two countries continued in this strained and critical condition during the greater part of 1804. Bonaparte insisted that the Spanish dockyards should repair the French ships in Ferrol and Cadiz,—which was indeed one of the conditions of the convention of October 19, 1803, concealed from Great Britain,—and should permit seamen to pass by land from one port of Spain to another, and from France through Spain, to complete their crews. He consented indeed that they should go in small bodies of thirty or forty, but the vigilance of the British officials could not be deceived. The relations between France and Spain at this time were not inaptly described in the letter of Napoleon to the king, announcing his assumption of the imperial dignity. He styled him therein "ally and confederate." In June, 1804, an aide-de-camp of the emperor visited Ferrol and Madrid, charged to ascertain the condition of the ships and demand their completion. [151] The British minister could obtain no explanation of this mission, which naturally aroused his attention. [152] Spain in truth was no longer a free agent. On the 3d of July, Napoleon ordered his Minister of Marine to send to Ferrol the men still needed to man the ships there; and on the 19th of the month [153] the British admiral Cochrane, then blockading the port, remonstrated with the governor of Galicia upon this procedure as hostile to Great Britain. On the 3d of September, and again on the 11th, Cochrane wrote to his government that Spanish ships in Ferrol were fitting for sea, that three first-rates were expected from Cadiz, and that no doubt remained that the French, Spanish, and Dutch ships in the port were to act together. He had consequently found necessary to concentrate his force. [154] Immediately upon receiving this information, the British ministry notified the Spanish government that orders had been sent to their admiral off Ferrol to prevent any Spanish ships of war from entering or leaving that port. The ambassador at Madrid was directed to require that the armaments should be discontinued, and placed upon the same footing as before the war. He was also to demand a clear explanation of the relations existing between France and Spain. Unless satisfactory replies were given, he was ordered to quit Madrid.

At the same time the ministry took a more questionable step. Orders were sent to Cornwallis, to Cochrane, to Nelson, and to the naval officer off Cadiz to detain and send to England all Spanish treasure-ships; the intention being to keep them as a pledge until satisfactory arrangements with Spain were made. In consequence of this, on the 5th of October, four British frigates stopped, near Cadiz, four Spanish vessels, of the same class but of inferior armament. The disparity of force was not great enough to justify the Spanish commodore in yielding; and an action followed in which one of his frigates blew up. The other three surrendered and were taken to England. Curiously enough, the news of this transaction had not reached Madrid when the British representative, on the 10th of November, left the city. The final discussions between him and the Spanish government went on in complete ignorance of so decisive an event; but as he could get no explanation of the agreements between France and Spain, he persisted in demanding his passports. On the 12th of December, 1804, Spain declared war.

That Great Britain had just cause for war can scarcely be denied. She now for the first time came into contact with Napoleon's claim that it was, not merely the interest, but the bounden duty of every maritime state to join his attempt to crush her. [155] Upon this principle he justified his policy of coercing all into such hostilities, and formulated at a later day the maxim, "There are no neutrals." The subsidy paid by Spain, calculated on British rates of expenditure, was annually worth to France fifteen ships-of-the-line and two hundred thousand troops; [156] but against Napoleon's further extension of his principle, by suddenly calling into activity the Spanish navy, Great Britain's only safeguard was to insist upon the latter's remaining unarmed. The Spanish government, having promised not to arm, suddenly and without explanation began to equip vessels in Ferrol,—an act which, coinciding with the passage of French seamen through Spain to that place, fairly excited alarm and justified the orders not to allow Spanish ships to enter or leave the port.

The seizure of the treasure-ships is less easily excused, though the obloquy attending it has been unduly heightened by the tragical explosion. Its best palliation lies in Great Britain's previous experience that, in the commercial decadence and poverty of Spain, the treasures of the colonies were a determining factor in negotiations. While they were on the sea, Spain temporized; when they arrived, she stiffened. The purpose was to retain them as a pledge, to be restored in case of a peaceable issue; as Swedish merchantmen were embargoed in 1801, and released when the Armed Neutrality dissolved. A Spanish naval historian, while censuring other acts of Great Britain, says: "The mere detention of the division from America, carrying specie which might be used in behalf of French preparations, could have been overlooked as an able and not very illegal means of bettering the prospects of the English reclamations, in consequence of the scanty satisfaction they obtained from our Court;" and again: "If all the circumstances are impartially weighed, ... we shall see that all the charges made against England for the seizure of the frigates may be reduced simply to want of proper foresight in the strength of the force detailed to effect it." [157] The action, nevertheless, was precipitate, and extenuated by no urgent political necessity. Nelson, who certainly was not averse to strong measures, directed his captains to disobey the order, which he at first thought came only from Cornwallis; for, he said, "I am clearly of the opinion that Spain has no wish to go to war with England." [158]