In September 1868, the Revolutionary Committee of Puerto Rico launched the Grito de Lares (Cry of Lares) revolt against Spanish rule in the island, carrying as their standard a flag conceived by pro-independence leader Ramón Emeterio Betances and embroidered by Mariana "Brazos de Oro" Bracetti with flag-making materials provided by Eduvigis Beauchamp Sterling.

The fusion of the Dominican and Cuban flags to make the Puerto Rican Lares flag was aimed at promoting the union of neighboring Spanish-speaking Greater Antilles—the single-nation islands of Cuba and Puerto Rico, and the Dominican Republic in the two-nation island of Hispaniola—into an Antillean Confederation for the protection and preservation of their sovereignty and interests.

Yet at the same time, other historians claim that, despite the absence of primary sources to validate the flag, there is a long oral tradition of testimonies that authenticate it.

According to the Archivo Digital Nacional de Puerto Rico (ADNPR) (National Digital Archive of Puerto Rico), the flag, considered to be La Coronela, the most important flag that was used by the first company commanded by the colonel of the armies, was captured in 1868 by Spanish Captain Manuel Iturriaga, who led the repression of the revolutionaries of Lares, in the Piedra Gorda neighborhood of Camuy, Puerto Rico after it was discovered on the farm of a revolutionary buried in one of two wooden boxes alongside hundreds of cartridges for militia rifles.

Determined to affirm the strong bonds existing between Cuban and Puerto Rican revolutionaries, and the union of Cuban and Puerto Rican struggles for national independence and fights against Spanish colonialism, on December 22, with the knowledge and approval of their fellow Cuban rebels, Terreforte, vice-president of the committee, and around fifty-eight fellow members gathered at the no longer existent Chimney Corner Hall in Manhattan, unanimously adopted the Cuban flag with colors inverted as the new revolutionary flag to represent a sovereign "Republic of Puerto Rico," replacing the Lares flag, which had been used by revolutionaries as the flag of a prospective independent Puerto Rico since their attempt at self-determination in 1868, but was eventually rejected, as it represented a failed revolt, a sentiment strongly supported by Lola Rodríguez de Tío, Puerto Rican poet, pro-independence leader, and committee member, who spent her later life exiled in liberated Cuba.

[16][17] In 1868, Puerto Rican pro-independence leader Ramón Emeterio Betances, urged Mariana Bracetti to knit the revolutionary flag of the Grito de Lares (Cry of Lares), using as design the quartered flag of the First Dominican Republic and the lone star of the Cuban flag, with the aim of promoting Betances’ idea of uniting the three neighboring Spanish-speaking Caribbean Greater Antilles of Puerto Rico, Cuba, and the Dominican Republic into an Antillean Confederation for the protection and preservation of their sovereignty and interests.

No official document in Puerto Rico provides the exact dimensions of the flag's shape, cross, and five-pointed star.