Spain is home to the world’s oldest active military unit.
In 1248, King Ferdinand III of modern-day Spain successfully completed the Siege of Seville — part of the ongoing effort to reclaim the Iberian Peninsula from Muslim rule — with the assistance of a plucky fighting group known as the Band of Castile. Said to be impressed by the bravery of this band of fighters, Ferdinand designated it a permanent division under his service, thus inaugurating what is now regarded as the world’s oldest active military unit.
The unit was reorganized numerous times over the following centuries as it took on a series of name changes, from the King’s Guard Colonelcy under Philip IV, to the Regiment of Castile under Philip V, to its current identity as the King’s Immemorial Infantry Regiment. No matter the moniker, the unit has participated in virtually every major conflict in the country’s history, including the 18th-century War of the Spanish Succession and Napoleonic Peninsular War, as well as overseas efforts that both aided the American Revolution and later fought the burgeoning superpower in the Spanish-American War.
Nowadays, the King’s Immemorial Infantry Regiment is largely charged with providing security at the Spanish army headquarters of Palacio de Buenavista, with other members assigned to service in the automobile and music divisions. Many of its duties are ceremonial, such as the palace’s monthly changing of the guard, or the traditional induction of the heir to the throne as an honorary soldier in the unit. While the call to arms is no longer a regular occurrence, this ancient regiment remains ready to aid the monarchy in any way it can, even if that means simply ensuring a smooth drive for palace personnel or fostering good vibes by striking up a jaunty tune.
