Conquest of the Desert The Conquest of the Desert ( ) was a military campaign directed mainly by General Julio Argentino Roca in the 1870s with the intent to establish Argentine dominance over Patagonia , which was inhabited by indigenous peoples . Under General Roca , the so - called Conquest of the Desert extended Argentine power into Patagonia and ended the possibility of Chilean expansion there . Argentine troops killed more than a thousand Indians and displaced over 15 , 000 more from their traditional lands . Ethnic European settlers developed the lands for agriculture , turning it into a breadbasket that made Argentina an agricultural superpower in the early 20th century . The Conquest is commemorated on the 100 peso bill in Argentina . The Conquest is highly controversial . Apologists have described the Conquest as bringing civilization , while revisionists have labeled it a genocide . One revisionist , Jens Andermann , has noted that contemporary sources on the campaign indicate that the Conquest was intended by the Argentine government to exterminate the indigenous tribes , an example of genocide . First - hand accounts stated that Argentine troops killed prisoners and committed " mass executions . " The 15 , 000 Indians taken captive " became servants or prisoners and were prevented from having children . " Apologists perceive the campaign as intending to conquer specifically those groups of Indians that refused to submit to Argentine law and frequently carried out brutal attacks on frontier civilian settlements . In these attacks , Indians stole many horses and cattle , killed men defending their livestock , and captured women and children to become the slaves or brides of Indian warriors . Some persons have been dismissed from public positions for advocating apologist views : for instance , Juan José Cresto was labeled a " racist " and forced to resign as a director of the Argentine National Historical Museum because he " said the Indians were violent parasites who attacked farms and kidnapped women . " A history teacher in Pampa Province was fired for " telling a radio station that Roca deserved praise for putting Indians to flight and opening Argentina ' s frontier to European settlers . " This recent debate between Conquest apologists and revisionists is usually summarized as " Civilization or Genocide ? " . Background . The arrival of the Spanish colonists on the shores of the Río de la Plata and the foundation of the city of Buenos Aires during the 16th century led directly to the first confrontations between the Spanish and the local Indian tribes , mainly the Querandí ( also called the Pampas ) . The Spanish had purchased the Buenos Aires hinterland from the local Indians to be used for cattle raising . This use displaced most of the animals traditionally hunted by the natives . The Indians responded by attacking the towns , killing settlers and releasing or driving off many cattle and horses from the farms . In retaliation , the Spanish colonists built forts and defended themselves from the frequent attacks . The frontier dividing the colonial farms and the Indian territories gradually moved outwards from Buenos Aires ; at the end of the 18th century , the Salado River was the boundary between the civilizations . Many Indians were forced to abandon their tribes to work on the farms . Some assimilated or intermarried with the white population . The group known as gaucho s developed from working on the ranches . After Argentina achieved independence in 1816 , the provinces had numerous conflicts as they struggled over how to organize . Once these were settled , the government wanted to quickly occupy the lands claimed by the young republic ( in part to prevent Chile from encroaching on it ) . It also wanted to increase the national agricultural production and offer new lands to prospective immigrants . In 1833 Juan Manuel de Rosas in Buenos Aires Province and other military leaders in the Cuyo region coordinated offensives to try to exterminate the resistant indigenous tribes , but only Rosas had any success . By this time Chile had founded Punta Arenas in Magellan Strait in 1845 , which threatened the Argentine claims in Patagonia . Later in 1861 Chile began the occupation of the Araucanía , which alarmed Argentine authorities because of its rival ' s growing influence in the zone . Chile had defeated the Mapuche in their central region . This indigenous tribe had strong language and cultural ties to the nomadic tribes on the east side of the Andes , with whom they share the same language . In 1872 the indigenous leader Calfucurá and his 6 , 000 followers attacked the cities of General Alvear , Veinticinco de Mayo and Nueve de Julio . They killed 300 settlers and drove off 200 , 000 head of cattle . These events were a catalyst for the government to mount the Conquest of the Desert . The Indians drove the stolen cattle from the incursions ( " malones " ) to Chile through the Rastrillada de los chilenos and traded them for goods . The historian George V . Rauch notes evidence that Chilean authorities knew about the origin of the cattle and consented to the trading in order to strengthen their influence over Patagonian territories . They expected eventually to occupy those lands in the future . Alsina ' s campaign . In 1875 Adolfo Alsina , Minister of War under President Nicolás Avellaneda , presented the government with a plan which he later described as having the goal " to populate the desert , and not to destroy the Indians . " The first step was to connect Buenos Aires and the " Fortines " ( fortresses ) with telegraph lines . The government signed a peace treaty with chieftain Juan José Catriel . But he broke it a short time later , as together with chieftain " Namuncurá " and 3 , 500 warriors , he attacked Tres Arroyos , Tandil , Azul , and other towns and farms . The casualties were higher than in 1872 : Catriel and Namuncurá ' s forces killed 400 settlers , captured 300 , and drove off 300 , 000 head of cattle . Alsina attacked the Indians , forcing them to fall back , and leaving " fortines " on his way south to protect the conquered territories . He also constructed the 374 km long trench named Zanja de Alsina ( " Alsina ' s trench " ) . It was supposed to be a fortified border to the unconquered territories . Three metres wide and two metres deep , it served as an obstacle to cattle drives by the Indians . The Indians continued taking cattle from farms in the Buenos Aires Province and the south of the Mendoza Province , but found it difficult to escape as the animals slowed their march . They had to confront the patrolling units that followed them . As the war went on , some Indians eventually signed peace treaties and settled among the " christians " behind the lines of forts . Some tribes allied with the Argentine government , standing neutral or , less often , fighting for the Argentine army . In return , they were granted periodical shipments of cattle and food . After Alsina died in 1877 , Julio Argentino Roca was appointed Minister of War , and decided to change the strategy . Roca ' s campaign . Julio Argentino Roca , in contrast to Alsina , believed that the only solution against the Indian threat was to extinguish , subdue or expel them . At the end of 1878 he started the first sweep to " clean " the area between the Alsina trench and the Negro river by continuous and systematic attacks to the Indian settlements . On 6 December 1878 , elements of the Puán Division under Colonel Teodoro García clashed with a war party at the Lihué Calel heights . In a brief but hard fought battle , 50 Indians were killed , 270 captured , and 33 settlers were freed . Numerous armed encounters would follow , until by December 1878 , over 4 , 000 Indians had been captured and 400 killed , 150 settlers freed and 15 , 000 head of cattle recovered . With 6 , 000 soldiers armed with new breech - loading Remington rifles , in 1879 he began the second sweep reaching Choele Choel in two months , after killing 1 , 313 Indians and capturing over 15 , 000 . From other points , southbound companies made their way down to the Negro River and the Neuquén River , a northern tributary of the Negro River . Together , both rivers marked the natural frontier from the Andes to the Atlantic Ocean . This attack led to a large migration of Mapuches into the zone around Curarrehue and Pucón , Chile . Many settlements were built on the basin of these two rivers , as well as a number on the Colorado River . By sea , some settlements were erected on the southern basin of the Chubut River mainly by Welsh colonists in y Wladfa . The final campaign . Roca followed Nicolás Avellaneda as president . He thought it was imperative to conquer the territory south of the Negro River as soon as possible , and ordered the 1881 campaign under the control of Colonel Conrado Villegas . Within a year Villegas conquered the Neuquén Province ( he reached the Limay River ) . The campaign continued to push the Indian resistance further south , to fight the last battle on October 18 , 1884 . The last rebel group of over 3 , 000 members under the command of chieftains Inacayal and Foyel surrendered two months later in present Chubut Province . Border clashes . To counteract the Argentine conquest of Patagonia , the Chileans supplied arms , ammunition and horses to their Indian allies . On 16 January 1883 , a 10 - man section of a platoon of the Argentine Army in pursuit of a large Indian war party , ran into an ambush in the Pulmarí Valley set up by Chilean soldiers , and in the engagement that followed Captain Emilio Crouzeilles along with Lieutenant Nicolas Lazcano and several privates were killed . On 17 February 1883 , Lieutenant - Colonel Juan Díaz , at the head of a 16 - man Argentine infantry detachment , was trailing a war party of 100 to 150 Indians . Upon reaching Pulmarí Valley , they were surrounded by the Indians and around 50 Chilean soldiers . Heavily outnumbered , the Argentine soldiers skillfully outfought their attackers , including a bayonet charge mounted by the Chilean detachment . On 21 February 1883 , according to Argentine Army Major Manuel Prado , 150 - 200 Indians armed with Winchesters and Martini - Henri rifles attacked an Argentine Army detachment operating on the Argentine - Chilean border , and in a four - hour engagement killed or wounded 22 Argentine soldiers at a cost of some 100 warriors . Further reading . < / div >