The Battle of Vargas Swamp (Spanish: Batalla del Pantano de Vargas) fought on July 25, 1819, was an engagement of Bolívar's campaign to liberate New Granada. The battle involved a joint Venezuelan and Neogranadine army commanded by General Simón Bolívar against the III Division of the Spanish Royalist Army commanded by Colonel José María Barreiro. The Battle of Vargas Swamp is considered one of the most important battles of the Colombian War of Independence, as it cleared the path for the Patriot army to advance towards Santafé de Bogotá, while also demoralizing the Royalist troops. Vargas Swamp was also the bloodiest battle of the 1819 New Granadan liberation campaign.

The battle came as a result of Bolívar trying to outflank Spanish forces by capturing the provincial capital of Tunja through the Toca road, doing this would enable the Patriots to cut off the Spanish army's supply and communication lines to Santafe de Bogotá, while also allowing the Patriots to gain the lead in the race to capture the lightly defended viceregal capital. The Royalists however caught wind of this plan and placed their forces on favorable ground in order to block them near a chokepoint between the towns of Tibasosa and Paipa. The battle lasted 6 hours, with the Royalist army having the advantage of being on higher ground as well as better equipment and better training.

This battle was difficult for Bolívar's forces who by 5pm looked like they would lose, with the Royalists almost encircling and destroying the Patriots. However a cavalry attack by a force of Llanero Lancers under the command of Lt. Colonel Juan José Rondón coupled with an infantry attack by the British Legion under Colonel James Rooke were able to break the Spanish lines and force them to withdraw. These actions turned defeat into victory for the Patriots.

Bolívar's army narrowly bested the royalist army in spite of the exhaustion of the troops after climbing the Páramo de Pisba, and crossing the swamp. This battle and the next victory over the Spanish by the Boyacá Bridge secured the independence of New Granada.

The battle was fought in an area between the towns of Paipa and Tibasosa known as Vargas swamp, which now no longer exits.

After Bolívar's army had crossed the Andes Mountain Range at the Paramo de Pisba in early July 1819 he arrived to the town of Socha, his army of Venezuelan and New Granadan troops as well as a British Legion were in a sorry state, his troops lacked uniforms and had lost all their horses as well as cattle along with some 100 dead, 500 sick, and a loss of a large amount of munitions. Over the next few days his army rested with the help of the local people of the Tunja Province (now Boyacá Department). Their assistance would be vital as they would provide food, horses, as well as tend to the sick troops, the women of these villages reportedly tore up their dresses and any clothes they could find in an effort to sew new uniforms for the naked army. Bolívar would also be able to recoup some of his forces as a large amount of locals joined his army or were conscripted.

Colonel José María Barreiro commander of the 4,000 strong III Division of Expeditionary Army of Costa Firme, the main Spanish Royalist force in the kingdom, had been garrisoned in the capital of the province, Tunja at the time of the Patriot invasion. Barreiro was surprised that Bolívar had crossed through the Paramo de Pisba especially during the winter rain season. Having heard rumours of potential invasion by the rebels in late June of 1819 he had dispersed his troops to guard the various mountain passes (except Pisba) that he thought Bolívar would take, thus at the time he had found out of the presence of Patriot forces at Socha he only had 1,000 troops with him at Tunja with some 400 guarding Santa Fe and another amount of troops scattered throughout the Altiplano Cundiboyacense. Over the next few days Barreiro began receiving intelligence reports concerning the composition of Bolívar's army revealing that he was at a numerical disadvantage, however in his letters to the viceroy he expressed confidence in his forces as they were better equipped, better armed, and had formal military training compared to mixed group of soldiers and peasants that made up Bolívar's forces.

During the following days leading up to the battle small detachments of the Patriot Vanguard clashed with patrolling Royalist troops at the town of Corrales. On July 10, Barreiro now forced to respond, sent a detachment to the town of Topaga and Corrales to block them where his troops would inflict a loss on the Patriots, however this was counteracted when Patriot cavalry forced them back to Corrales. The two armies would clash again at the Battle of Gámeza on July 11, which was indecisive for both sides. As a result of this, Bolívar realized that he was still not strong enough to face Barreiro in an open battle and discarded his initial strategy of a frontal assault on the town of Sogamoso, instead opting for a flanking maneuver through the Cerinza Valley with Barreiro falling back towards the town of Paipa to block him.