Calatrava, once a barrio in the town of San Agustin (then called Badajoz) in Tablas Island. During pre-Spanish period, the place was called "Andagao", named after a medicinal plant growing in abundance everywhere in the locality especially in places along the shore.

Around 1810, the first settlers in Andagao migrated from Banton and Romblon islands, as well as in central parts of Tablas Island, in search of lands more suitable for agriculture. The Simaranhons, Sibalenhons and Bantoanons were the first settlers of the municipality and joined later by migrants from Odiongan of which, like them, spoke Asi. Today, this group of people made up the great portion of its residents, while the northern barangays of Linao, Pangulo and Talisay have significant Romblomanon residents. Onhan settlers originally from central Tablas decided to settle in the southern barangay of Balogo.

Around 1838, Andagao was organized into a fundacion (settlement) attached to visita (village) of Odiongan under the pueblo of Banton by the Spanish colonial authorities. The following year, a Spanish friar named Padre Jose Aznar from the parish of Banton visited the place and planned the construction of its first Roman Catholic church made of wood and limestone. Eleuterio Asuncion, the barrio's cabeza de barangay spearheaded its construction. After the church was completed, Andagao immediately progressed and developed. In 1850, people started using family names beginning with letter "F" as decreed by Spanish Governor-General Narciso Claveria issued on 21 November 1848.

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Wikipedia