Battle of Montes Claros
The Battle of Montes Claros was fought on 17 June 1665, near Vila Viçosa, between Spanish and Portuguese as the last major battle in the Portuguese Restoration War. It was a great Portuguese victory and is considered as one of the most important battles in the country's history.
By 1665, the Portuguese Restoration War had been raging for 25 years. Despite numerous setbacks, King Philip IV of Spain was determined to crush the Portuguese insurrection. After the disastrous southern campaign in 1662 that culminated in the Battle of Ameixial, the Spanish court evaluated the performance of the Spanish Army and came to the conclusion that the war could only be ended by decisive action. The court believed that the insurrection could only be ended by the capture of a major city or by the complete destruction of the Portuguese Army. Luis de Benavides Carrillo, Marquis of Caracena, a veteran of campaigns in Italy and the Netherlands, was appointed to lead the new invasion of Portugal. Carrillo had served as a field commander and as a military governor, and his organizational skills were lauded. Carrillo planned to end the war by capturing the Portuguese capital of Lisbon. To reach the city, he planned first to take Vila Viçosa, followed by Setúbal.
Once he was in command, Carrillo wanted to gather strength to ensue that he outnumbered the opposing Portuguese Army. However, the illness of King Philip caused the court to order him to procede with the invasion, as they feared that the death of Philip would strengthen foreign support for the Portuguese. The Spanish crown was also facing financial difficulties, and there was a legitimate fear that the army would be disbanded if the war continued.
The Portuguese were prepared and had foreseen such an attack. 3,500 men were moved from Trás-os-Montes in the north to Alentejo in the south. A further 7,800 men came from Lisbon, under command of António Luís de Meneses, who had beaten the Spanish in the Battle of the Lines of Elvas six years earlier. They were reinforced by a veteran English contingent of 2,000 men under the command of the Duke of Schomberg.
A veteran commander who had been defending the Portuguese border for over 20 years, Meneses was aware that there were any number of ways for Carrillo to invade the country. As such, he reinforced the border garrisons of Elvas and Campo Maior, hoping to harden the frontier defenses and in doing so influence the route Carrillo would take. Having been present during the Portuguese victory at Ameixial, Meneses was well aware that the Spanish faced logistical challenges when invading Portugal, and he planned to keep Carrillo's army trapped in the border hinterlands as long as possible. The Portuguese were also conscious of the failing health of the Spanish King, and Meneses suspected that this would coerce them to attack.
Carrillo's army moved into Portugal on 25 May. He first took Borba without resistance after it was abandoned by the Portuguese. He then laid siege to Vila Viçosa, which was better defended and offered a stiff resistance to the attackers.
The Portuguese decided to exchange land for time, as it was hoped that the rough terrain of the hinterlands would degrade Carrillo's army. Despite this strategy, Meneses was determined to engage the Spanish army, and he planned to choose the battlefield his men would fight on. The main body of the Portuguese army had set itself in motion towards the besieged city, but it stopped in Montes Claros, halfway between Vila Viçosa and Estremoz.
Carrillo, who was at that time furthering the siege of Vila Vicosa, was fast losing men to attrition. By June, attacks by Portuguese militias were taking a heavy toll on his lines of supply, Vila Vicosa continued to put up an unexpectedly fierce defense, and the Spanish court was demanding action. In spite of these setbacks, Carrillo continued to rely on his previous plans for the capture of Lisbon. However, when informed that Meneses's numerically inferior force was advancing on him from Estremoz, Carrillo decided to engage the Portuguese.
Meneses deployed his army in a defensive formation adjacent to and at the south end of a long ridge line. A dense cork oak forest lay further to the south of the Portuguese positions. By defending the space between these two terrain features, Meneses planned to limit the amount of Portuguese and Spanish units fighting at any one time and as such counter the superior Spanish numbers. He positioned his heaviest infantry, composed of seasoned veterans and mercenaries under the command of Frederic Schomberg, in two lines in this gap and ordered his artillery to support them. The rest of the Portuguese army was held in reserve and ordered to prevent the Spanish from scaling the ridge line. Carrillo was well aware of the Portuguese defenses and massed his cavalry and artillery for an all out attack on the gap between the ridge and the forest. 
The battle opened with the Spanish artillery firing into the Portuguese positions, opening gaps in the first line of infantry. The Spanish cavalry then charged the Portuguese lines and overran several units. The Portuguese infantry organized themselves into squares to fend off the cavalry, but this left them vulnerable to the Spanish artillery. The Portuguese cannon fired repeatedly into the ranks of Spanish cavalry, and inflicted many casualties. As the first Spanish charge retreated, Meneses ordered his first line back and consolidated it into the second line. When a Spanish cannonball killed Francisco da Silva Moura, the commander of the Portuguese contingent of the second line, Meneses took command in person.
A second Spanish cavalry attack and barrage again caused many casualties in the Portuguese infantry lines, but was forced to withdraw without having reached the second line due to the Portuguese artillery.
Carrillo then ordered a massive third charge, incorporating both cavalry and infantry, into the Portuguese defenses. The battle raged on and the fighting was extremely intense. The Count of Mertola, commander of the British contingent and military adviser, had his horse shot from underneath him and was almost captured by the Spanish. The Portuguese artillery in particular was devastating as shot after shot was fired into the advancing mass of Spaniards, while the Spanish cannon were soon forced to cease in their firing for fear of hitting their own men. The assault collapsed, and Spanish infantry and cavalrymen were pressed tightly together and became easy targets for the Portuguese. The Spanish cavalry alone suffered over 1,200 casualties in the third charge on the gap.
Though the Spanish and Portuguese armies remained mostly intact, the Spanish had placed all their hopes on the cavalry charges and started to lose hope. Having failed to breach Meneses's defenses, Carrillo began to slowly withdraw to the north.
After 7 hours of sporadic fighting, the Portuguese launched a counterattack. The Portuguese cavalry, which had until this point played no role in the battle, charged and overcame the weakened left flank of the Spanish army. The Spanish army started to fall apart and fled in disorder towards Badajoz, leaving behind all their artillery and many dead and wounded. Thousands of Spanish soldiers were captured and made prisoners, with eight Spanish generals being among the captured.
In the days after the battle, the Portuguese harassed the retreating Spanish, inflicting many casualties. A great many arms and armaments were captured by the Portuguese. Total Spanish casualties for the battle and its aftermath amounted to 4,000 killed and 6,000 captured, while the Portuguese suffered some 700 killed.
The Battle of Montes Claros effectively ended major combat operations during the Restoration War and definitively secured Portuguese independence from Spain. The Spanish did not attempt another invasion, and signed the Treaty of Lisbon three years later, recognizing Portugal's new ruling dynasty, the House of Braganza.
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