Leomil was born in the 9th century, when the king awarded the warrior Leodmiro for his fights against the Moors. From the 13th century onward, it became the only Portuguese commandery of the Order of Roncesvalles, in Navarre, which administered it for six centuries. From chickens and wheat paid in rent to vast estates spread across the country, Leomil prospered under this unique rule.
Today, few inhabitants remain, and agriculture continues to mark the rhythm of this village where markers bearing the initials "RV" (Roncesvalles) still survive, a living memory of the ancient order.