The title above translates to the 15 Martyrs of Bicol.
January 4, 1897 (5 days after Rizal's execution). 15 Martyrs were executed. 11 in Bagumbayan (now Luneta Park) while 4 of them were exiled or died in prison. When the Katipunan was discovered, a message was sent by Governor-General Blanco to all governors to organize mass arrests throughout the country. From September 6 to October 10, 1896, 15 of them collaborated with the Katipunan. They were accused of conspiracy, and collaborating against the anti-colonialism group which sparked the Filipino Revolution against the Spaniards.
11 of the 15 who were sentenced to death by musketry at Bagumbayan were:
Rev. Inocencio Herrera
Rev. Gabriel Prieto
Rev. Severino Diaz
Manuel Abella
Domingo Abella
Camilo Jacob
Tomas Prieto
Florendo Lerma
Macario Valentin
Mariano Melgarejo
Cornelio Mercado
4 of the 15 either died or exiled in prison were:
Leon Hernandez
Ramon Abella
Mariano Arana
Mariano Ordenanza
A monument was built to honor the 15 martyrs, it was unveiled on November 30, 1923, at Naga City, Camarines Sur, and it is named Plaza Quince Martires.
Sources:
Lead Image from http://www.thebackpackadventures.com/2014/08/featured-destination-plaza-quince.html
https://cbanga360.net/2010/01/04/the-fifteen-bicol-martyrs-of-1897/