Santiago el Mayor was 530 ton galleon of the Portuguese navy which was part of the Squadron of Castile which was part of the Spanish Armada. She was a typical ship of her size and a sister ship to San Juan (el Menor), San Pedro (el Mayor), San Felipe y Santiago, Asunción, Nuestra Señora del Barrio and San Medel y Celedón
Santiago el Mayor was built in Guarnizoin in 1584 as part of a class of galleons. They were all similar. Armed with 24 guns and crews of about 85 sailors and about 100 soldiers on each one. They were good sailing boats and all made it back to Santander or Laredo after the Armada.