Spanish Civil War
In April 1937, he was part of Ignacio Cardona's cell consisting of Glaucia Acosta, Dwight Adams and several Republican soldiers making their way to Barcelona. The group made camp to rest for the night and during the campfire, the group was attacked by Republican soldiers who had mistaken them for Nationalist soldiers.
By May 1937, Miguel and the group had made their way to Barcelona. Both him and Dwight were woken by a commotion which they believed was an intruder. After Glaucia cornered the intruder, they interrogated him, who revealed that he was Norbert Clarke, an Assassin sent by the British Brotherhood to asist them, showing them a letter as proof. He claimed that he was responsible for eliminating the entire Templar branch in Talinn in 1936. Convinced that he was an Assassin, Miguel and the Assassins introduced themselves to him.
The next day, Miguel and the Assassins trained with Norbert, who easily defeated them. They later followed Ignacio to a firefight between anarchists and nationalists. Miguel argued with Dwight as he believed that they should side with the government while Dwight believed that they should side with the anarchists. The two were later interrupted by Ignacio, who had unleashed the Koh-i-Noor which produced serpent-like projections. Before Miguel and Dwight were consumed by it, Ignacio managed to resist the artifact and throws it away.
As the Assassins checked on him, they were attacked by the Black Cross Albert Bolden, who targeted Norbert. While Miguel and the Assassins fought the Templar, they were unable to prevent him from taking Ignacio away. "Norbert", who was in fact the Templar Rufus Grosvenor, would later turn the Assassins against Ignacio, convincing them that their leader had been compromised by the Black Cross. Believing that both Ignacio and Albert would go after them, the Assassins later holed up in a war-torn village.
Manipulated by Grosvenor
As Ignacio and Albert approached the village, Miguel and Dwight launched a surprise attack on the both of them, though they were easily taken down. While Dwight questioned Ignacio for the truth, Miguel held Albert at gunpoint, who told him to go ahead and open fire. He pleaded Ignacio to use the gem so that they could end the war. Ignacio however, was unwilling to do so as it would cost him his life. In response, Dwight told him that their lives would weight nothing against millions, as "Clarke" had told him about Germany, about what Hitler was planning to his people.
During the conversation, Dwight attempted to attack Albert from behind, leading to a fight. As Dwight held the Black Cross, Miguel took the opportunity to slash Albert's stomach with his Hidden Blade. However, before Miguel could deliver the finishing blow, Albert deflected his attack and caused him to stab Dwight who was holding him from behind. As Dwight collapsed on the ground, Bolden punched Miguel in the face and rescued Ignacio from Glaucia, who had slipped behind her lover and held a knife under his throat.
Realizing that Miguel fled, two men then followed his tracks to the town church, where Grosvenor was waiting for them. The Templar was standing over a pit of anarchist bodies, killed by Franco's men, and who ranted about humanity needing the firm guiding hand of the gods. Entering the church too, Glaucia and Miguel took aim at them and had Ignacio and Albert to surrender their guns. Grosvenor told of how his master had followed Ignacio's bloodline, hoping for optimum conditions - but the fact that he was a male was a clear failing to fully controlling the gem.
Nevertheless, he offered Ignacio the Koh-i-Noor in the hope that he may still try. Upon touching the gem, the Assassin created the illusion of the diamond shattering under its own power and summoned creatures of energy who stampeded into the walls of the church bringing it crashing down upon all of them.