During the Central American Civil War (1826 - 1829), he was still young, he distinguished himself in the Battle of Mexico in 1828 and in the seizure of the Fortress of San Fernando de Omoa in Honduras in 1832.

Malespín stood out as the leader of the Conservative party and collaborated with General Rafael Carrera in Guatemala in his battles against Francisco Morazán and the liberal Creoles of the State of Los Altos.

Agustín whom Morazán had released from prison that night - did not know that Carrera had made Morazán think that he had obtained the triumph and then had crushed his forces.Carrera then sent Malespín to warn the Quiché and Cakchiquel communities to prepare again to fight the Quetzaltecos Creoles, and then left for Quetzaltenango determined to excite the Altes liberals; upon hearing this news, most of the members of the council fled and the few who remained wanted to retract and apologize for having tried to, but while the indigenous people of the region were chasing the Creoles who fled, Carrera arrested the members of the council who had stayed and then sent them to be shot, despite the claims of the Altense population who murmured "Massacre!

As a result, the liberal Creoles were weakened and diminished, and the capital conservatives frightened; for their part, the indigenous populations of Quetzaltenango realized that they had a strong ally in Carrera.

[9] Where he is remembered for his fondness for rum and his volatile character that caused excesses of his troops that burned down the city and looted the sacred objects of its churches.

But on 15 February 1845, despite returning "victorious" from the campaign in Nicaragua, the Army ignored him and the Legislative Power declared his election as President of the Republic void, and he was replaced by Vice President Guzmán; In addition, due to the abuses committed - to which was added the execution of the priest Dionisio Urcuyo y Crespín - Bishop Viteri y Ungo excommunicated him on 23 February 1845 in the Cathedral of San Salvador.