It began in summer 1590 when Philippe-Emmanuel de Lorraine, Duke of Mercœur, the governor of Brittany, offered the port of Blavet to King Philip II of Spain so that he could harbour his fleet.

There is no doubt that the failure of the enterprise of England represented a serious setback to Philip II's strategic thinking, although its repercussions were felt much more on a psychological level than a material one, since Casado Soto[1] had accurately documented that of the 123 ships that sailed from La Coruña, "only" 31 were lost, of which only 3 were galleons, the rest being the urcas and other smaller vessels.

[2] On the other hand, the invasion project was not abandoned and during the last years of the reign of Philip II there were several attempts to carry it out, within the increasingly generalized confrontation to which the two monarchies were forced in different maritime and ground based scenarios, among which the Brittany campaign stands out.

On the other hand, shortly after the return of the Armada, a general mobilization of troops had been ordered in all the coastal provinces with which to face the expected response from the English,[5] although the arrival of winter temporarily distanced the fear of an immediate counterattack thus restoring confidence.

The resultant decrease in tension allowed the infantry units that returned with the Armada to be sent to winter in the interior, thus alleviating Santander of the burden of billeting the large number of attack forces that were concentrated there.

Drake soon realized his mistake but, for reasons that have never been sufficiently explained, decided to continue the attack and after overcoming the initial weak resistance, managed to land the bulk of his forces on the beach of Santa Lucía on May 4.

Their losses were estimated at between 1,000 and 1,500 men, while on the Spanish side, three galleons were set on fire by their own crews to prevent them from falling into enemy hands, although the galleys that fled to the Betanzos estuary were saved.

These bloody actions represented a serious setback for Drake who had to return to England after losing half of his troops, some 10,000 men between dead and wounded, to which the loss of nine ships had to be added, seven of them off Lisbon, all without being able to obtain any immediate benefit.

This method of attack by means of fire ships had manifested itself in all its effectiveness during the 1584-1585 siege of Antwerp by Alexander Farnese and on the night of August 7, 1588, when used by the English against the Grand Armada anchored in Dunkirk.

In this sense, the opinion of Don Juan Maldonado is very illustrative, who, in October 1589, already explained to the King the need that there is in this Navy for some vessels that, being long-range sailboats, are capable of carrying artillery and some men to spot and attack the corsair ships that they find, for having seen some that they have sailed in in recent days, they cannot be persued with the big ships, nor are the pataches suitable, for they are small, thus the need for medium vessels of 150 to 200 tons; their draught is of great consideration, since being light is what is intended.These defensive plans were still in force when, after the winter of 1589–1590, Philip II addressed the Council of War requesting their opinion on what could be done during that year with the Navy concentrated in Ferrol.

[16] At its meeting on May 18, 1590, the council's response could not have been more expressive, since it considered that "time being so far advanced and how few soldiers and mariners they have to be able to undertake any important enterprise", a most intriguing one would be for 15 or 20 large ships to be chosen and adding to those another 12 or 15 flyboats, putting in them elite soldiers who could be chosen from the Tercios that are dedicated to them… patrol the coasts of these kingdoms and purge and secure these seas of corsairs and await and escort the fleets from the Indies and that the other ships may be discharged and the remaining infantry go into garrisons and in this way Your Majesty will save a lot of costs and be able to entertain yourself and wait for a better time and situation to carry out the main enterprise.This position by those who considered that the "main business" continued to be the invasion of England, had been adopted with the conviction that they did not have all the necessary elements to issue a well-founded opinion, and they declared as much to the King, indicating that "in order to realize what Your Majesty commands, being a business of such consideration, it was necessary for the Council to be more prudent and informed of the things that are being discussed"[17] A few weeks later, on July 6, 1590, the War Council learned of a letter that Diego Maldonado[18] had sent from Nantes in which he relayed an offer from Philippe-Emmanuel de Lorraine, Duke of Mercœur of the "port of Blavet (today called Port-Louis, Morbihan), wherein to assemble his Navy, and everything in Brittany that is in his charge and government", expressing the hope with which he awaited "the help and protection of Your Majesty to free him from the violence and power of the heretics".

[22] The French succession issue had become one of the fundamental objectives of Philip II's foreign policy for whom the possibility of a Calvinist accessing the throne of the neighboring country was an impossible risk to assume.

But at the end of 1588, and protected by the crisis that the failure of the Grand Armada had caused, Henry III of France ordered the assassination of the Duke of Guise and his brother, unleashing a true public uprising known as the Day of the Barricades whose most notable effect, on the part of the League, was to gain control of the city of Paris.

In fact, the army that carried out the "invasion" of Aragon under the command of Don Alonso de Vargas, was reunited with the cover story of "passing through France",[23] where since 1590, a contingent of lancers had already been operating, which had been gathered with the contributions of different prelates and lords required for it.

[34] To transport the tercio to Brittany, the creation of a squadron made up of 4 galeasses, 2 galleys and up to 31 vessels including ships, flyboats, pataches, galizabras and zabras under the command of Sancho Pardo was ordered.

[37][38] It is therefore not surprising that this calamitous voyage had a very negative effect on the condition of the soldiers which, at the time of their landing, caused such an unfavorable impression among those who, expecting the best soldiers in Europe, found men who were so broken, skinny and emaciated and who moved the Breton ladies to compassion who had to tend to the more than 600 sick among them,[39] however shortly thereafter, the population's opinion changed substantially when they were able to witness the performance of these same men who, confronting the Calvinist troops led by Henri, Duke of Montpensier, Prince of Dombes, in a disciplined manner, were able to raise the siege under which the town of Dolo was subjected.

After raising the siege of Dolo, they began to besiege Hennebont where their troops dragged six large cannons from the galeasses, opening a sufficient breach to force the inhabitants to capitulate, delivering the town from a sack with 20,000 scudi ransom.

[42] This circumstance allowed direct confrontation between both contingents of auxiliary troops that reached its most dramatic expression when, on May 22, 1592, the Spanish came to the aid of the town of Craon, which was besieged by the Huguenot army with the support of the English and Germans.

The performance of Águila's tercio was decisive, managing to raise the siege after inflicting a severe defeat on his opponents, causing a general rout after leaving more than 1,500 dead on the field and capturing all their weapons, ammunition and supplies.

[43] In fact, the initiative was always in the hands of the Spaniards who had a solid base in Blavet after the construction of the so-called "Fort del Águila" (Citadel of Port-Louis) by the men of the Tercio themselves with the help of the galley slaves, under the direction of the engineer Cristóbal de Rojas.

But while control over Blavet remained firm throughout the entire campaign, the same could not be done in other important ports, as happened with Saint Malo, which was occupied by Don Juan del Águila in 1591, only to be abandoned shortly thereafter due to the lack of sufficient troops to keep it.

This was especially true with the port of Brest, which was one of the priority objectives throughout all those years and where in 1594 the Quélern peninsula was occupied, leaving a force made up of three companies of infantry, roughly 400 men, under the command of Captain Tomé de Paredes.

The so-called "Fort of the Lion (El León)" was hastily erected whence, exhibiting extraordinary courage, they remained for several months until, on November 19 of that same year, they succumbed to French and English forces led by Sir John Norris, who were vastly superior in numbers.

[47] From the very beginning of the campaign, Spain stressed the importance of having safe ports at the entrance of the English Channel that would serve to guarantee communications with Flanders and as support bases for the planned invasion of England.

For this reason, when Águila's Tercio was dispatched in 1590, it was already arranged that some of the ships used in the transport of the troops would remain in Blavet in order to collaborate in some of the ground operations and try to exercise, at the same time, control of maritime traffic in that area of the channel.

[58] For his part, Pedro de Zubiaur was in favor of round ships, indicating, not without a certain irony, that "three galleys are enough… two to go out and the other as a hospital",[59] for the many sick men that bad weather caused among those poorly fed forces.

But the decrease in the number of prizes and the fact that, as Zubiaur said, "there are no longer open villages to loot or burn",[75] had a very negative impact on the maintenance of the units themselves, since, until then, the criterion of the Court was that they be maintained from the spoils of their captures.