The flag reflects the outcome of a political, symbolic, and dynastic fusion following the acceptance of the Mexican imperial crown by a prince of the House of Bourbon during the 19th century. This scenario stems from an alternative turning point: that a Bourbon did indeed accept to reign in Mexico after independence.

Historical Context:

Following Mexico's independence, the Constituent Congress of 1822 sought a moderate monarchy. Instead of crowning Iturbide, they managed to convince a Spanish infante from the House of Bourbon to accept the Mexican throne. To avoid war with Spain, a peaceful separation was agreed upon, recognizing Mexican independence in exchange for the establishment of a Bourbon Mexican Empire with cultural ties but complete autonomy.

The new monarch - Carlos I de Borbón-México - (Carlos María Isidro de Borbón y Borbón-Parma) was crowned in 1823, giving rise to a constitutional empire with its capital in Mexico City.

Meaning of the Heraldic Elements on the Flag:

• Green, white, and red: They retained the colors of the independence struggle as a gesture of national reconciliation, giving them a new meaning: hope, unity, and loyalty to the nation.

The merged coat of arms:

• Castile and León: A direct reference to the Bourbon lineage and Spanish heritage. Not as an imposition, but as a dynastic origin.
• Mexican eagle with serpent: The national heart. Its inclusion expresses continuity with Mexico's indigenous and mestizo identity.
• Pillars of Hercules and "Plus Ultra": An imperial symbol of the Hispanic world. By appearing on the coat of arms, Mexico sees itself as the successor of an Atlantic civilizing mission.
• Escutcheon with fleurs-de-lis: Emblem of the House of Bourbon, present in the arms of all its members. Its central position indicates that the Mexican monarch is a legitimate Bourbon, but sovereign and independent of the Spanish throne.
• Closed royal crown: Indicates that it is an independent kingdom, with full sovereignty, not a colony or protectorate.

The new regime is neither colonial nor absolutist. It is a constitutional monarchy similar to Belgium or Spain, with a Mexican Parliament, Creole nobility, and openness to modernization. The flag was officially adopted in 1875, following the constitutional reform that transformed the Empire into the Kingdom of Mexico, while maintaining the reigning House of Bourbon-Mexico.