Cartes Neptuno, Brujula y Quadrante: Con que goza la Espana por tu mano De estas ilustres Sciencias lo importante.

"Your eloquence is divine, o MEDRANO, because the muses see your wisdom and that you strive for the noblest of arts and sciences, and thus Pallas gave you the intelligence for his military architecture; and Urania from her sphere the pure light to measure her orbs with prudence.

For this horrible fire Vulcan gave the lightning of his thundering forge; and to find a path to the Ocean, Neptune provided maps, a compass, and a quadrant: with which Spain enjoys through your hand the importance of these illustrious Sciences.

"[4] A sonnet from Manuel Pellicer y Velasco, a disciple and friend of Sebastián Fernández de Medrano, written in 1688: " A torch that, when extinguished, you shine brightly, a Sun that, amidst clouds, turn [to] your rays, Cupid of the sciences that you adorn, Eloquence and all its greatness.

"[7] Colonel de la Llave acknowledges Medrano's Academy and credits him with significantly enhancing military training by combining practical and theoretical education.

[11] Driven by what he describes as "zeal and glorious ambition," Sebastian Fernández de Medrano found deep satisfaction in exploring the extensive literature on the art of warfare.

He participated in four military campaigns across Castilla la Vieja during 1660 and 1661, serving under the governance of the Duke of Osuna, primarily in roles stationed at simple garrisons along the frontier.

Sebastian Fernández de Medrano reflected deeply on his experiences and the influences that shaped his military career, noting the profound respect he held for the Marquess of Gastañaga, the Governor and Captain General of Flanders.

Sebastián wrote: "Since the aforementioned Lord Marquess loved the glory of the Military so much...he highly esteemed the officers of his tercio who were inclined to service and applied to everything required to acquire their good judgment."

Despite this supportive environment, Medrano faced skepticism from his peers regarding his intense focus on mathematics, a subject he pursued with relentless dedication despite being deemed "crazy" by other officers.

Encouraged by this confidence in his abilities, Medrano accepted the challenging role of director for the new academy, stepping into a pivotal position that would influence the future of military training in Spain.

"[11] The King further instructed the Duke to implement the necessary arrangements to ensure Medrano received his captain's salary and commanded his company, overriding any previous orders that might conflict with this decision.

Moreover, King Charles II emphasized the broader strategic importance of fostering such educational initiatives, urging the Duke to "favor greatly those who dedicate themselves to this profession, as it is necessary to have qualified individuals in this field everywhere."

Recognizing the significant progress achieved by the Royal Academy of Mathematics, the Duke of Villahermosa once again conveyed his commendation of Sebastian Fernández de Medrano's efforts to King Charles II in a persuasive letter.

Johann Hugo von Orsbeck, Archbishop-Elector of Trier, upon learning of Medrano's presence through officers who had previously been his students, sought his expert opinion on the fortifications of Koblenz and its prominent castle, Ehrenbreitstein.

In the letter dated August 2, 1689, Juan Hugo of Orsbeck, the Archbishop Elector of Trier, expressed his deep appreciation and respect for the training provided by the Director of the Royal Academy of Brussels, Sebastian Fernández de Medrano.

Sebastian Fernández de Medrano recalls a notable instance where a disciple of his, appointed to the siege of Casal di Monferrato, earned the commendation of the Duke of Savoy.

On May 20, 1688, he issued an order acknowledging Medrano's invaluable service and provided him with the necessary support to continue his work at the Academy, thus ensuring that his contributions would endure despite his personal hardships.

He has published at his own expense eight books, all related to these military arts, with great clarity for the shortest teaching and understanding of the disciples, which has given him so much credit among foreigners that many princes desire his disciples and send subjects to his Academy to learn from him..."[11] The Marquess of Gastañaga praised Medrano's increasing merit and the continual excellence he displayed in his military and academic endeavors, praising his "zeal" and "valor" both in action and in his dedication to the mathematical arts.

Sebastian Fernández de Medrano's continued dedication and service were met with further royal favor when King Charles II agreed to increase his monthly salary by forty escudos.

The Marquess of Gastañaga had noted the substantial financial contributions from Medrano's wife's inheritance—more than eight thousand escudos—used for publishing educational materials, which necessitated a significant investment due to the complexity of the subjects and the need for translation into Spanish.

This royal decree, issued on July 14, 1692, in Madrid, not only provided for Medrano's immediate family but also acknowledged his long-standing service and the unique value of his contributions to the military through his expertise in mathematics.

Recognizing both Medrano's dedication and the tangible benefits that subsequently arose in service to His Majesty, the Elector of Bavaria, Marquess of Bedmar, and Prince of Vaudemont also deemed it appropriate to bring this to His Royal Highness's attention, as evidenced by the subsequent letter from Prince de Vaudemont: "...although on different occasions Your Majesty has shown appreciation for the intelligence, rightly justified by the reports and information that have been presented to Your Majesty about the person and qualities of Sergeant General of Battle Don Sebastian Fernandez de Medrano, director of the Royal Academy of Mathematics in this Court, and although the transcendent benefit that his intellect and abilities bring to Your Majesty's royal service needs no further qualification than that which he already has in this army and in all the courts of Europe, I have nevertheless thought to add to the many and authoritative declarations that endorse his proficiency in all the subaltern faculties of mathematical science..." Brussels, January 20, 1696 - Charles Henri of Lorraine, Prince of Commercy, Prince of Vaudémont[11] Continuing his efforts until the year 1699, when Lord Carlos II passed away, Medrano started to seek recognition for his greater merit and services, specifically requesting the rank of General of the Artillery.

The Duke of Montalto also supported the promotion, stating: "...If the reward for your useful and commendable work depended on my discretion, you would have the benefits you deserve, and if I were in the Court, I would be your agent in the request for the rank you are seeking, because, as the King, whom God protects, has foreseen and I know, you set an example for no one else, and I promise that you will achieve what you desire.

Sebastián Fernández de Medrano includes two lengthy letters of recommendation from the elector of Bavaria and the Marquess of Bedmar, dated March 2 and July 21, 1701, which reiterate the merits and services of the director of the Academy.

However, an exception was made for Don Sebastian Fernandez de Medrano, the General of Battle and Director of the Military Academy, who was permitted to continue collecting his salary as usual.

However, Medrano's contributions were overshadowed, according to Cermeño, by the misfortune of being Spanish and working during a period when Spain's military innovations were not as celebrated as in other eras, as noted in "La Mina" (1898).

[18] In his work "Perfecto bombardero," published in 1699, Don Sebastián Fernández de Medrano claimed to have invented a unique and innovative method for constructing the chamber of mortars, introducing what he called the "pear" shape.

[7] The Sargent General of Battle, Don Sebastián Fernández de Medrano, director of the Royal Military and Mathematics Academy of the Low Countries in Brussels, introduced his own variation of the proportional method in fortification in order to enhance the structures balance and defensive capabilities by precisely dividing inner sides and adjusting proportions, especially for pentagons, to improve fire coverage and minimize vulnerabilities, and boost the fort's defensive effectiveness and resilience.

This occurred on January 22, 1700, the same day His Majesty issued a decree to establish the Military Academy in Barcelona and instructed that notices be posted in the War Secretariat to recruit teachers.