Miramón was born in Mexico City in 1831 into a very traditional family of partial French heritage. He was the son of Colonel Bernardo de Miramón and his wife Carmen Tarelo, who apparently had twelve offspring. Some of them were Joaquin, Carlos and Mariano; these appeared next to his brother in his various military campaigns. At the age of 15, he fought bravely but was taken prisoner while a cadet by the U.S. Army in the September 1847 defending on Chapultepec Castle in the Mexican–American War.