The enmity over the territorial dispute continued after 1942 and concluded following the Cenepa War of 1995 and the signing of the Brasilia Presidential Act agreement in October 1998.

It revolved around whether Ecuador's territory extended beyond the Andes mountain range to the Marañon (Amazon) river, including the Amazonian basin.

[6] The dispute was again brought into the spotlight after the signing of the Salomón–Lozano Treaty in March 1922 by the governments of Colombia and Peru, which at that time was ruled by Augusto B. Leguía.

The Salomón–Lozano Treaty was unpopular in Ecuador as well, which found itself surrounded on the east by Peru, which claimed the territory as an integral part of its republic.

"[12] The social situation of Peru at that time was undergoing major changes, with the social reforms begun by president Augusto B. Leguia (which, he claimed, were aimed at improving roads, sanitation, industrial development, and promoting the general welfare of Peru's indigenous population) being continued by president General Oscar Benavides.

[2] According to the testimony of Col. Luis Rodríguez,[13] the Ecuadorian forces at the disposal of the Army Border Command in El Oro (Lieutenant Colonel Octavio A. Ochoa) after the incidents of 5 and 6 July were as follows: As a result of the rising tensions on the border during 1939 and 1940, the Peruvian President Manuel Prado authorised in December 1940 the creation of the Agrupamiento del Norte (Northern Army Detachment).

[14] According to Peru, Ecuadorian Army troops from the garrison of Huaquillas, a town on the bank of the Zarumilla river, which then served as the status quo line in the extreme left of the Ecuadorian-Peruvian border, crossed into the Peruvian border post at Aguas Verdes, a town directly in front of Huaquillas, and opened fire on a Peruvian Civil Guard patrol.

The mission consisted of bombing the Ecuadorian post of Quebrada Seca, where they had concentrated the bulk of their anti-aircraft artillery and placed machine guns.

[2] According to Peruvian accounts, instead of parachuting to safety, Quiñones chose to sacrifice himself by crashing his damaged aircraft onto the Ecuadorian position, rendering the battery out of action.

The fact that the patrol boat was the target as well as the subsequent defense of it carried out by Ecuadorian troops prevented valuable explosives located nearby from being attacked and ignited.

The Peruvian military authorities of La Tina protested and asked for an explanation, sending a sergeant and two soldiers to receive an answer after a two-hour ultimatum.

[23] Fire was exchanged beginning at 2 p.m. Peruvian Commander César Yánez, head of the 7th Cavalry Regiment, supported by a company from the 19th Infantry Battalion and a battery from the 8th Artillery Group, crossed the river on July 28 and took Macará, encountering little opposition.

Later, with the support of the company commanded by Captain Fernando del Risco, the Ecuadorian Army remnants in nearby Vado Limón were also defeated.

[2] On July 25, in the Chacras sector, strong Peruvian contingents preceded by a tank surrounded a group of 25 soldiers commanded by Ecuadorian Lieutenant César Edmundo Chiriboga González, who refused to surrender and fought to the death, along with his troops.

In the place where he and his men died, the Peruvians put together a cross with a plaque that read, "Lieutenant César E. Chiriboga González and 25 soldiers, fallen on July 25, 1941, in the line of duty.

According to Second Lieutenant Hugo Ortiz Garcés [es], who would be killed the next day, the Ecuadorian Yaupi outpost and its Gazipum garrison was attacked from July 31 to August 1, 1941, by no less than 100 soldiers from the Peruvian Army, armed with eight machine guns.

[26][23] On August 2, 1941, in Gapizum, on the banks of the Santiago River, the Ecuadorian post of ten soldiers, commanded by 20-year-old Second Lieutenant Hugo Ortiz Garcés [es], was again attacked and, unlike the previous day, overrun by Peruvian forces.

Ortiz refused to surrender and was killed in action by the Peruvian soldiers, who buried him wrapped in the flag of the small Ecuadorian detachment in charge of guarding the Yaupi area.

After half an hour of combat, the Ecuadorians were defeated, consolidating the Peruvian domain[clarification needed] in the Yaupi and Santiago rivers.

[26] On July 25, the Peruvian destroyer Almirante Villar set sail from Zorritos with the mission of entering Ecuadorian waters and carrying out patrol and reconnaissance tasks in the area.

The core of Peruvian aviation was made up of a squadron of five NA-50 fighters, known as Toritos, which were a version of the North American P-64 and had been delivered by the United States in May 1939.

[32] On August 31, 1941, and facing a delicate political and national security situation, President of Ecuador Carlos Alberto Arroyo del Río decided to retain a considerable part of the Ecuadorian Army to protect the capital, Quito.

[33] This military order was given due to intelligence reports coming from the intelligence services of Brazil, Chile, and the United States, informing President Arroyo del Río and the Ecuadorian military high command that Peru was less than 48 hours from Guayaquil, leaving from Machala and Puerto Bolívar, the second port of Ecuador.

[26] By the end of August 1941, Peru occupied the coast: the provinces and cantons of El Oro, Puerto Bolívar and began the blockade of Guayaquil, the main commercial port and naval base of Ecuador.

A civil administration was established in order to provide a sense of normalcy to the Ecuadorian citizens that lived under occupation, which relieved the military from certain efforts.

[39] Also prior to the evacuation, a general state of disorder had taken over due to a lack of administration, with both countries reporting looting by some Ecuadorian troops fleeing north.

[35] Additionally, a resistance had been established by both Ecuadorian citizens and army members, through which acts of sabotage were carried out against the Peruvian occupying force.

The exiled Cantonal Council held its first plenary Session on January 18, six days after the withdrawal of Peruvian troops from Ecuador.

Thus, some 78 km of the Ecuadorian-Peruvian border were left unmarked for the next fifty years, causing continuous diplomatic and military crisis between the two countries.

Peruvian analysts have speculated that President Velasco used the nullity thesis in order to gather political support with a nationalistic and populist rhetoric.