Le colonel don Sébastian Guerrero était un homme de haute taille, aux traits durs et accentués, au teint bronzé et à la physionomie hautaine ; les quelques fils argentés mêlés à sa noire chevelure montraient qu'il devait avoir passé le milieu de la vie^ bien que ses membres robustes, sa taille droite et l'éclat de son regard dénotassent que les années n'avaient pas encore eu de prise sur cette organisation énergique.

Gustave Aimard wrote multiple volumes about Latin America and the American frontier. Oliver Aimard was born in Paris. As he previously stated, he was the offspring of two married individuals, "but not to each other". His father, François Sébastiani de la Porta (1775-1851), was a commander in Napoleon's army and a representative of the Louis Philippe government. Sebastiani was married to the Duchess of Coigny. In 1806, the couple had a daughter, Alatrice-Rosalba Fanny. The mother died shortly after she was born. Fanny was reared by her grandmother, Duchess of Coigny. Aimard was placed as a baby with a family that were paid to raise him. By the age of nine or twelve, he was sent off on a herring boat. Later, about 1838, he served briefly with the French Navy. After one more trip to America (when he claims he was adopted into a Comanche tribe), Aimard returned to Paris in 1847, the same year his half-sister, Duchess de Choiseul-Pralin, was cruelly killed by her noble husband. Reconciliation or acknowledgement by his biological family did not occur. After serving briefly in the Garde Mobil, Aimard returned to the Americas.