By Allison Fedirka

At Geopolitical Futures, our model highlights the Western Hemisphere’s stability and calmness when compared to the rest of the world, much of which is in crisis. South America particularly stands out because, despite the differences between some of the continent’s countries, it has not experienced full-scale interstate warfare in over 80 years. During this time period, many parts of the world have been fraught with active military conflicts. Such a prolonged absence of interstate war deserves further examination given that South America did experience multiple violent interstate wars in its first 120 years of independence. However, since the Chaco War between Bolivia and Paraguay ended in 1935, security and military matters in South American countries have remained largely focused on domestic issues. The few times interstate tensions increased to a military level, the countries involved never engaged in a full-scale prolonged war.

Post-Independence Warfare

South American countries gained their independence from European colonial powers during the 1810s and 1820s. France’s invasion of Spain during the Napoleonic Wars clearly signaled the latter was in a state of decline. A weaker Spain and previous revolutions – American and French – had already set a precedent for successful colonial independence movements.

However, acquiring independence from European powers marked only the beginning of several interstate wars in the region that shaped countries’ current borders. First came the Cisplatine War (1825-1828) between present-day Brazil, Argentina and Uruguay. The conflict was over a territorial dispute between modern-day Uruguay and Brazilian states Rio Grande do Sul and Santa Catarina. Shortly before this war in the Rio de la Plata Basin ended, the Gran Colombia-Peru War (1828-1829) started in the Andean region. The Gran Colombia area consisted of modern-day Ecuador, Colombia and Venezuela. However, this war played out primarily along the Peru-Ecuador border and involved heavy naval warfare along the Pacific coastline. Less than a decade later, Peru was at war again, this time allied with present-day Bolivia against Chile in the War of the Confederation (1836-1839). After a brief lull in interstate warfare, Rio de la Plata experienced the six-month Platine War in 1851, which saw Argentina and Brazil compete for regional power and influence over Uruguay, Paraguay and Bolivia.

South America Wars

Then came arguably the two most geopolitically significant interstate wars for South America: the War of the Pacific (1879-1883) and the Triple Alliance War (1864-1870). The War of the Pacific saw Peru and Bolivia fight against Chile. Chile won through strategic use of amphibious warfare to overcome a major, natural battlefield obstacle –  the Atacama Desert – and weaken enemy supply lines. This war also held grave geopolitical consequence for Bolivia as it lost direct sea access.

In the Triple Alliance War, Paraguay fought against Brazil, Argentina and Uruguay. This war is by far the most devastating full-scale, interstate conflict the region has experienced to date. It decimated Paraguay. Towards the end of the war, it is said young adolescent boys were given fake beards and forced to fight at the Battle of Acosta Nu. The observation of this battle’s anniversary coincides with national Children’s Day in Paraguay. Scholars debate exact numbers but the general consensus is that an estimated 60 percent to 70 percent of Paraguay’s total population died during this war, including approximately 90 percent of adult males. It took over a century for Paraguay to recover its population balance and gender ratio after the war.

The last major interstate war in South America was the Chaco War (1928-1935) between Paraguay and Bolivia, two poor, landlocked countries that had lost significant territory in previous conflicts. One of the war’s most notable features is that it marked the first time large-scale aerial warfare was employed on the continent. That said, air combat was a rarity as both sides relied more on reconnaissance and close infantry support. The inhospitable terrain of the Chaco region, which is sparsely populated, made it difficult to advance troops and small armored vehicles through the area. The challenging climate also inadvertently converted several cavalry units into infantry, as many horses did not survive the harsh conditions. This conflict was the last and bloodiest interstate war in South America during the 20th century.

A Move Away from Interstate Conflict

After the Chaco War, a definite shift can be observed in the region. While South America still confronted violence and security issues, it never entered full-scale, interstate warfare again. There have been several incidents in South America during the last 80 years in which one country decided to demonstrate military prowess and strength against another. However, the intensity and duration of these incidents did not escalate to the point of all-out war. Ecuador and Peru’s three military encounters in the 20th century and Argentina’s war with the U.K. over the Falkland Islands each lasted between four to nine weeks and the fighting was limited to confined areas.

In the last 80 years, the greatest security threats prompting military engagement in South American countries have been largely domestic. In this time period, South America has seen the emergence of narco-terrorists, guerilla groups and military juntas. With the exception of Guyana, all South American countries experienced some type of military rule during the 20th century. National militaries have also been deployed to combat organized narco-terrorist groups like the Revolutionary Armed Forces of Colombia (FARC) and Shining Path in Peru. This said, militaries have been involved in domestic conflicts throughout the region’s post-independence history. Civil wars and separatist movements requiring military intervention have occurred in Colombia, Argentina, Chile, Uruguay Brazil, Venezuela, Paraguay and Ecuador.

Geographic Factors Preventing War

South America has three unique geographic characteristics that discourage modern warfare between nation-states in the region. First, South America behaves much like a large, isolated island in the Western Hemisphere. Mexico, Central America and the Caribbean create a physical separation between South America and the world’s largest global power, the United States. To put this distance in perspective, the time it takes to fly from San Francisco to Tokyo is roughly equivalent to the direct flight time between New York City and Buenos Aires. Furthermore, South America’s location in both the Western and Southern hemispheres means it is less exposed to major global conflicts. The continent is physically isolated from Eurasia, where many of the world’s deadliest wars have been waged. Therefore, South American countries have largely managed to avoid being drawn in to these conflicts.

Another notable feature is the limited number of nation-states on the continent. Asia, Europe and Africa each consists of approximately 50 countries. Central America and the Caribbean contain 19 countries. South America has only 12 sovereign states. The continent’s surface area is about 1.75 times greater than Europe’s surface area and the equivalent of about 60 percent of Africa’s. There are simply fewer countries in the region and therefore fewer opposing interests, which has resulted in less potential for conflict.

Lastly, geographic barriers coincide with national borders, thereby naturally and significantly reducing the possibility of conflict. Interdependence between countries breeds war; the natural barriers between countries discourage high degrees of interdependence. The Andes mountain range runs the length of South America and severely impedes any east-west land passage across the continent. The Andes are significantly taller than their northern counterpart, the Rockies. The tallest 100 peaks in the Andes range in height from 19,600 feet to 21,800 feet, while the Rockies’ 100 tallest peaks range from 12,300 feet to 14,400 feet. Just to the west of these mountains along the Pacific coast lies the Atacama Desert, the driest desert in the world. It creates a 600-mile no man’s land between Peru and Chile and also includes part of the Bolivian border. To the east of the Andes lies the Amazon rainforest. This thick, impassable rainforest overlaps with the national borders of six South American nations and provides a natural buffer in these border areas. The Pantanal, the world’s largest tropical wetland, lies just south of the Amazon in Brazil. This swampy area also creates physical obstacles for crossing parts of Brazil’s borders with Bolivia and Paraguay. Lastly, the Chaco region, particularly the area where Bolivia’s and Paraguay’s borders meet, is semi-arid and generally inhospitable. The climate fluctuates seasonally between extremely dry weather and flooding.

The Rio de la Plata Basin differs from the rest of South America’s geography due to the absence of natural geographic barriers. The basin hosts a strategic river system that runs through very fertile lands. This river system allows for easy access from the coast to the interior. The basin is also extremely flat. It is one of few places in the entire region where national borders are porous and people and goods can easily be transported. Therefore, it is not surprising that this region has been the site of multiple interstate wars, including the Triple Alliance War, which was the continent’s bloodiest conflict.

In addition to geography, we must also look at the mechanization of warfare to better understand why South American countries have not engaged in interstate wars for the last 80 years. From the wars of independence up until the Chaco War, warfare in the region was simplistic by modern standards. The 20th century saw major evolutions in warfare mechanization. This is particularly true for armored tanks and air power, which are seen as essential support features in modern warfare. Tanks enable militaries to bring in and protect large numbers of ground troops, while airstrikes support the advancement of offensive teams. The vast majority of South American terrain simply does not allow for tank mobility. In addition, military aircraft need to travel longer distances to reach their targets, which necessitates more frequent refueling and makes air missions more vulnerable. The natural barriers between nations also mean that airbases and targets are significantly harder to reach than one would think by looking at a map. In short, the continent’s geography makes it difficult to employ equipment and tactics that are now essential in modern warfare.


The 80-year absence of interstate warfare in South America is noteworthy. From the standpoint of modern geopolitics, this is a truly a rare event. Geography discourages most of these countries from forming strong interdependent relationships and also makes it difficult to use key elements of modern warfare. Significant technological advancements in infrastructure, transportation and military hardware would be necessary to overcome these geographic challenges. Given our current model of the Western Hemisphere, this absence of interstate warfare in the region can be expected to continue for the foreseeable future. As a result, domestic issues – drug trafficking, guerrilla groups, disease, natural disasters, etc. – will remain by far the largest security threats to South American nations.

Allison Fedirka
Allison Fedirka is a senior analyst for Geopolitical Futures. In addition to writing analyses, she helps train new analysts, oversees the intellectual quality of analyst work and helps guide the forecasting process. Prior to joining Geopolitical Futures, Ms. Fedirka worked for Stratfor as a Latin America specialist and subsequently as the Latin America regional director. She lived in South America – primarily Argentina and Brazil – for more than seven years and, in addition to English, fluently speaks Spanish and Portuguese. Ms. Fedirka has a bachelor’s degree in Spanish and international studies from Washington University in St. Louis and a master’s degree in international relations and affairs from the University of Belgrano, Argentina. Her thesis was on Brazil and Angola and south-south cooperation.