Encouraged by his uncle, Martín de Urdaneta y Troconis, who had been employed in
Santa Fe,
Viceroyalty of New Granada, as the chief accountant of the Court of Accounts of the Real Audiencia of Santa Fe, Urdaneta traveled to that city in 1804 with the intention of developing his studies. He lived several years in Santa Fe, acquiring experience in the administration of military affairs. On July 20, 1810, a junta was formed in Santa Fe: one of the many independence movements that were beginning to take shape across the entire continent following the establishment of the
Caracas Junta in April of that year; Urdaneta joined the movement. He was incorporated into the first battalion of the patriot army of New Granada on November 1, 1810, as a lieutenant, and the following year fought in the
Campaña del Sur of New Granada. Following the Battle of Santa Fe in 1813, he was captured by the royalists and imprisoned for a few months before being liberated.
Admirable Campaign Simón Bolívar had been exiled from Venezuelan territory after the collapse of the
first republic he had established in 1811, but by 1813 he was fighting the
royalists in the New Granada region. It was during this time that Urdaneta was able to join Bolívar's revolutionary army. Bolívar's
Admirable Campaign to reclaim Venezuela proved to be a stage for Urdaneta. He distinguished himself under the command of colonel
José Félix Ribas on July 2, 1813, in the
Battle of Niquitao, and was decisive for the patriot victory at the
Battle of Taguanes against the royalist forces of Colonel Julián Izquierdo. Following the patriot victory and the establishment of the
Second Republic of Venezuela, in the report before the
New Granada Congress at
Tunja, Bolívar described Urdaneta as:
"worthy of recommendation and deserving of all esteem from the government for the valor and intelligence with which he distinguished himself in action." From that moment on he led numerous military actions, among which stand out the , the
1814 Caracas Exodus, the (after which he was promoted to lieutenant-general at only 26 years of age), the
Capture of Maracaibo, and the March to
San Carlos in 1821 that liberated the
Province of Coro and set the stage for the
Battle of Carabobo. He did not participate in the Battle of Carabobo since Bolívar considered that the exhaustion his troops had suffered during the march was too great. In view of Urdaneta's service, Bolívar requested at this moment that he be promoted to General Officer. Following the Battle of Carabobo in 1821, with Venezuela independent and after years of service to the patriotic cause, Urdaneta became one of Bolívar's closest friends and collaborators.
Conspiración Septembrina In 1828 Urdaneta, then Minister of War and presiding over the Cabinet, was in charge of judging the alleged traitors behind the
September Conspiracy by which an attempt was made to assassinate Bolívar, then president of
Gran Colombia. Convinced without any doubt that
Francisco de Paula Santander was the head conspirator, Urdaneta, along with the majority of the ministers in the Cabinet, sentenced him to death. Bolívar was afraid for the stability of the union between New Granada and Venezuela, so he forced Santander to lifelong exile instead. However, conflicts such as this one, in addition to the assassination of
Antonio José de Sucre in 1830, ultimately led to the collapse of Gran Colombia and; therefore, the union for which Bolívar had sacrificed so much to maintain since independence was achieved. Throughout his life, Urdaneta also served as Chief of Army Staff and as Minister of War and Navy. Bolívar called him
"El Brillante" ("The Brilliant"), for his remarkable sense of strategy in battle; a name now used to refer to him in Venezuelan historiography. He is considered to have been "the most loyal of loyals to Bolívar". His loyalty to the patriotic cause and the ideals of Bolívar was perpetuated in the words he once said to him: == Presidency ==