His father, a former Captain in the local militia, wanted to send him to study at the Artillery Academy in Toledo, Spain, hoping that his son would follow in his foot steps with a military career.

[2][3] On February 24, 1892, Vélez Alvarado together with Sotero Figueroa, Francisco Gonzalo Marín and Modesto A. Tira placed an ad in the newspaper "El Porvenir" calling for a meeting amongst those who believed in the independence cause.

A result of this meeting was the founding of the "Club Borinquen", a political organization in favor of Puerto Rico's independence.

[2][3] According to some accounts on June 12, 1892, Vélez Alvarado was at his apartment at 219 Twenty-Third Street in Manhattan, when he stared at a Cuban flag for a few minutes, and then took a look at the blank wall in which it was being displayed.

Almost immediately he visited a nearby merchant, Domingo Peraza, from whom he bought some crepe paper to build a crude prototype.

The original contents of the letter in Spanish are the following:[6] La adopción de la bandera cubana con los colores invertidos me fue sugerida por el insigne patriota Francisco Gonzalo Marín en una carta que me escribió desde Jamaica.

Yo hice la proposición a los patriotas puertorriqueños que asistieron al mitin de Chimney Hall y fue aprobada unánimemente.Which translated in English states the following: The adaptation of the Cuban flag with the colors inverted was suggested by the patriot Francisco Gonzalo Marín in a letter which he wrote from Jamaica.

[2] Puerto Rico never gained its independence, instead it was annexed by the United States under the terms of the Treaty of Paris of 1898, ratified on December 10, 1898, which put an end to the Spanish–American War.

[3][8] The President of the Puerto Rican Nationalist Party, Pedro Albizu Campos, was among those who were present when Vélez Alvarado died on January 16, 1948, in his home in Manatí.

[9] In the Plaza de la Historia, located in the Calle (Street) Patriota Pozo of Manati, there is a bronze bust of Vélez Alvarado.