Pey was mayor of Bogotá at the time of the Cry of Independence, also known as the ''[[Colombian Declaration of Independence|Florero de Llorente]]'' (Llorente Flower Vase) (July 20, 1810). On that morning, the history of the country changed; a group of criollosCriollos accused [[José Gonzalez Llorente]] of discrimination and riots broke out all over the city. Pey, as the mayor, tried to calm the populace. He proposed protective custody for Llorente, but by doing so he confirmed his culpability and thus fueled the insurgency.
That same day a ''[[Cabildo (council)|Cabildocabildo Abiertoabierto]]'' was established to decide the future of the city. The Cabildocabildo was formed by members of the criollanCriollo oligarchy, both [[RevolutionariesRevolutionary|revolutionaries]] and [[Royalist (Spanish American RevolutionsRevolution)|Royalistsroyalists]]. The Cabildo opted to create a ''[[Junta (Peninsular War)|Junta Suprema]]'' or (Supreme Governing Committee,) with Viceroy Amar y Borbón as president and Pey as vice president. Amar was sworn in in the early hours of the next day.<ref>[http://www.armada.mil.co/index.php?idcategoria=264636& Armed Forces of Colombia, events in history]</ref> However, he refused to preside over the junta, and as a consequence, that duty fell to Pey. Pey thus became the first Criollo to exercise executive power in the viceroyalty of [[New KingdomViceroyalty of Granada|New Granada]]. This Junta approved the Act of Independence, and Pey was one of the signers.
