The patron saint of Militello Rosmarino is Saint Blaise, celebrated on 3 February in the cathedral dedicated to him, originally named after Saint Nicholas of Myra.
The town's fief and castle, confirmed in 1371, were bought in 1536 by Antonio La Rocca of Messina, who obtained the title of baron; they later passed to Giovanni del Carretto, count of Racalmuto, and finally, in 1573, to Girolamo Gallego, son of Don Giovanni Gallego (himself born of an Aragonese knight and an Aztec princess) and husband of Donna Angela Rosso, descendant of the family that had owned the town since the time of the Martins. His son Vincenzo Gallego, invested with the lordship in 1600, together with his mother promoted the founding of the Dominican convent in 1615, and was approached by the inhabitants of the Marina di Sant'Agata seeking protection from frequent pirate attacks, after eight corsair galleys had landed on the beach in 1580, looting everything and enslaving many inhabitants. Over the course of the 17th century the Gallego family obtained the title of marquises of Sant'Agata and then, in 1658, that of princes of Militello.
