Twenty of the Longest Wars in Military History

For as long as humans have existed, they have fought. As a result, human history has witnessed many great battles. The earliest evidence of war dates back to at least 4,700 years BC. Here we look at some of the longest wars in history.

Historically, humans went to war for many reasons. Yet eventually, it almost always came down to religion, territory, and political ideology. However, many also believe that money is an excellent motivator of war.

Mercenaries were common in ancient battles. For example, when the first recorded war ended, the victorious Sumerians “carried away the weapons of Elam as spoils.”

Today, war is still profitable and many companies continue to earn billions from it.

Even though war is now swift and easy, especially for countries that spend trillions on their military, this was not always the case. Before technology and intelligence agencies wars would drag out for decades.

24/7 Wall St. has compiled a list of the longest wars in history. We curated the list after reviewing data and articles from various authentic sources. But, of course, wars had to follow diligent criteria to appear on the list.

For example, the conflict had to meet the definition of war: “An open and usually declared armed conflict between political entities such as sovereign states or competing factions within the same state, such as a civil war.” Moreover, conflict must have been sustained over time and intended to resolve political or territorial disputes.

20. Great Northern War

• Duration: 1700 – 1721 (21 years)
• Combatants: Russian Empire and allies, Swedish Empire
• Killed: 300,000
• Fought in: Denmark, Russia, and Nordic countries

In the early 18th century, Sweden was a dominant power in the Baltic region. However, three neighboring kingdoms, namely Russia, Denmark-Norway, and Saxony-Poland, decided to attack Sweden for land and resources. Hence, they formed a coalition after King Charles XI died and his 14-year-old son, Charles XII, was crowned king.

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England and Prussia also joined the coalition to gain more land and resources. After two decades of battle, Sweden retreated and surrendered its territory and wealth. The Great Northern War helped Russia grow into the superpower it is today.

19. The Peloponnesian War

• Duration: 431- 404 B.C. (27 years)
• Combatants: Greek city-states
• Killed: 100,000+
• Fought in: Greece, western Turkey, southern Italy

In this war, the Greek city-states fought against each other. One state was Athens, and the other was Sparta. Athens was an open city with a democratic rule of law. At the same time, Sparta was a closed city ruled by a selected few. The differences always kept the two cities in conflict. They had previously been at war but agreed to a truce.

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The ceasefire was tense. The war reignited after both sides failed to resolve the conflict diplomatically. After a decade of fighting, another truce was signed, which lasted only six years. Finally, in 405 B.C., with the financial help of Persia, Sparta’s navy was able to defeat Athens. Sparta drove the Athenians into starvation through a blockade and eventually forced them to surrender.

18. Thirty Years War

• Duration: 1618-1648 (30 years)
• Combatants: Protestant and Catholic German city-states, royal houses of Bourbon and Habsburg
• Killed: 8 million
• Fought in: Europe

As the name suggests, this war was a three-decade-long conflict between the Protestants and Catholics of 17th-century Europe. First, a dispute arose when Emperor Ferdinand II of the Holy Roman Empire forced his subjects to follow Catholicism despite a previous peace treaty giving the Roman subjects the freedom to choose and follow their faith.

Nobility in what is today Austria and the Czech Republic rebelled. Finally, both sides signed the Peace of Westphalia treaty after thirty years of battle. The treaty established official borders and started shaping how geopolitics is today.

17. Aceh War

• Duration: 1873-1904 (31 years)
• Combatants: The Netherlands and Aceh
• Killed: 90,000
• Fought in: Indonesia

The Aceh War was one of the most prolonged struggles against colonialism. Tensions began when the Dutch felt they had a claim to Sumatra, a large Indonesian island. However, the people of the Aceh region of Sumatra resisted Dutch rule, even though their sultan signed a treaty recognizing the sovereignty of the Netherlands in the area.

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Aceh’s army fought for decades using guerilla warfare. In the end, Aceh gained independence in 1949.

16. Wars of the Roses

• Duration: 1455-1487 (32 years)
• Combatants: England’s Royal houses: House of Lancaster and House of York
• Killed: 100,000
• Fought in: England

In the Wars of the Roses, the families of Lancaster and York fought for control of the British throne. The conflict started because Henry VI from the House of Lancaster was mentally ill and not fit to rule. However, both families felt entitled to the throne as they descended from the same bloodline.

Henry VII of the Lancaster’s became King when York’s Richard III died in battle. Soon after, Henry VII married a Yorkish princess to unite the houses and end the war. The war inspired George R.R. Martin’s novel series ‘A Song of Ice and Fire’, which then became HBO’s hit series ‘Game of Thrones’. The names of the warring families, Lancaster and York, were used to create the fictional houses of Lannister and Stark in the novel.

15. Guatemalan Civil War

• Duration: 1960-1996 (36 years)
• Combatants: Guatemalan rebels against the Guatemalan government
• Killed: 200,000
• Fought in: Guatemala

In 1954, a U.S.-backed coup deposed the country’s democratically-elected leader. Six years after the coup, the Guatemalan Civil War began. When Guerilla troops started attacking government forces it kickstarted a 36-year conflict with the Mayans. Kidnappings, torture, executions, and violence were commonplace.

Power in Guatemala frequently changed, either via elections or coups. Nevertheless, the war continued until 1996 when Alvaro Arzu, a Guatemalan politician, negotiated a peace deal.

14. Punic Wars

• Duration: 264-146 B.C. (43 years)
• Combatants: Roman Republic and Carthage
• Killed: 250,000
• Fought in: Areas around the Mediterranean Sea

Just like World War One, The Punic Wars started amongst more minor factions. However, they escalated when more prominent allies, namely Rome and Carthage, joined the conflict. The two fought a battle to claim the island of Sicily.

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Though Carthage was wealthy and had more battle experience, many of its leaders were corrupt and embezzled military funds. When Carthage’s mercenaries went unpaid, Rome defeated Carthage. They destroyed the city state and replaced it with one of the most powerful entities in the world.

13. Papua Conflict

• Duration: 1969-present (50 years)
• Combatants: Free Papua Movement and Indonesia
• Killed: 150,000
• Fought in: western New Guinea

When the Netherlands left west Papua in the 1960s it turned power over to Indonesia. As a result, residents of the west Papua Free Papua Movement fought a civil war. In December 2018, the movement killed 31 people in an attack and reignited the civil war. The Free Papua Movement claimed it had attacked Indonesian soldiers, but Indonesian authorities said those killed were construction workers.

12. Greco-Persian Wars

• Duration: 499 B.C.-449 B.C. (50 years)
• Combatants: Greek city-states and Persian Empire
• Killed: unknown
• Fought in: Greece, Asia Minor

A Greek city-state uprising against Persia led to one of the longest and bloodiest wars of the ancient world. The Persians could easily quell the assault by Greek city-states, but since Athens sent reinforcements in support of the rebellion, Persian leader Darius used this as a reason to attack Greece.

Though the Persian army was much more numerous, the Greeks were able to outflank and outmanoeuvre them on land and at sea. After 50 years of bitter fighting Persia agreed to a peace treaty.

11. Korean War

• Duration: 1950-present (69 years)
• Combatants: North Korea, South Korea, China, United States, NATO
• Killed: 1.2 million
• Fought in: Korean peninsula

Even though the U.S. military is no longer active in the Korean Peninsula, there was never an official peace treaty signed between North Korea and South Korea. Therefore, technically, the countries are still at war.

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There have been signs of improved relationships ever since the two heads of state met in 2018. However, tension remains high, with no end to it in sight.

10. Karen Conflict

• Duration: 1949-present (70 years)
• Combatants: Karen National Union and the Burmese Tatmadaw
• Killed: unknown
• Fought in: Myanmar

When Burma (Now Myanmar) began to set up its own government after independence from the British in 1948, many in the Karen ethnic minority felt excluded. Hence, they demanded self-sovereignty. However, there was optimism that the election of Aung Sang Suu Kyi, a Nobel Peace Prize winner and a popular leader throughout the country, could resolve the conflict.

However, the Karen National Union is still at war with the Myanmar army, and regularly carries out guerilla attacks.

9. Kashmir Conflict

• Duration: 1947-present (72 years)
• Combatants: India and Pakistan
• Killed: 80,000
• Fought in: Kashmir province

This conflict also started after the end of World War Two and is still yet to be concluded. The Kashmir conflict continues to divide two of the the largest countries in the world, India and Pakistan.

Recently, tensions between the sides reignited when Pakistan-based fighters killed dozens of troops in the disputed region of Kashmir. India responded with airstrikes on Pakistani soil.

8. Dutch War for Independence

• Duration: 1568-1648 (80 years)
• Combatants: Seventeen Provinces in the Netherlands against the Spanish King
• Killed: 100,000+
• Fought in: The Low Countries

The Dutch War for Independence, also known as the 80 Years’ War, marked the rise of Protestantism in Europe. Moreover, it signaled the end of Spanish supremacy in the region. After years of Spanish rule, protestant Dutch people started to resent their Catholic rulers. Hence, William of Orange began a revolt.

Even though Spain had a much larger military, its attention was divided between its ongoing battles with England and France. In the 1630s, the Netherlands allied with France. The two allies pushed into Spanish-controlled territories. After being outmatched by the combination of the Netherlands and France, Spanish leaders signed a truce in 1648.

7. Seleucid-Parthia War

• Duration: 238 B.C.-129 B.C. (109 years)
• Combatants: Seleucid Empire of Persia and the state of Parthia
• Killed: unknown
• Fought in: Mesopotamia, modern-day Iran, Central Asia

The Seleucid Empire ruled from Thrace in Europe to the border of India. Like many ancient empires, it faced internal and external battles that slowly eroded its power. The kingdom briefly lost control of Parthia (modern Iran) and regained it in a series of conflicts.

It was only one of the many battles they had to fight during the war. Eventually, the Arsacids, under the leadership of Mithridates I, launched their final attack to the Seleucid Empire, taking nearly all of its territory and the rest of Mesopotamia.

6. Hundred Years’ War

• Duration: 1337-1453 (116 years)
• Combatants: House of Plantagenet (or House of Anjou) of England and House of Valois of France
• Killed: 3.5 million
• Fought in: modern-day France

The British and French fought the Hundred Years’ War to determine who would control what is now France. The war lasted for over a century. For 116 years, The House of Plantagenet, rulers of England, and The House of Valois, descendants of earlier French kings, fought for control of the French throne following the death of Charles IV.

When European royal families mixed, their claim to the throne and titles became complicated. Both sides also had to deal with internal struggles during the war. However, House Valois, led by Charles VII, seized the opportunity presented by England’s Wars of the Roses and finally won the war.

5. Byzantine-Ottoman War

• Duration: 1265-1479 (214 years)
• Combatants: Byzantine Empire and the Ottoman Empire
• Killed: unknown
• Fought in: modern-day Turkey, western Asia Minor

The end of the Byzantine Empire and the Middle Ages in Europe came about because of the Byzantine-Ottoman Wars. The Ottoman Empire continued to grow during the 13th, 14th, and 15th centuries, while the Byzantine-controlled territory shrunk.

Ottoman ruler Mehmed II finally defeated the Byzantines after he seized the heavily fortified city of Constantinople. 

4. Byzantine-Seljuk War

• Duration: 1048-1308 (260 years)
• Combatants: Byzantine Empire and the Seljuk Turks
• Killed: unknown
• Fought in: Asia Minor and Syria

The Byzantines were involved in more than two centuries of conflict, the longest being the war with the Seljuk Turks. For 260 years, the Byzantines and Seljuks fought over territory in Asia Minor and the surrounding areas.

The Seljuk Turks lost some of their gained territories due to the Crusades. While the Byzantine Empire was preoccupied with other conflicts, it could not maintain its territory. As a result, the war ended after 260 years and further fueled the decline of the Byzantine Empire.

3. Arauco War

• Duration: 1536-1825 (289 years)
• Combatants: The Araucanian Indians of Chile and the Spanish Empire
• Killed: unknown
• Fought in: Modern-day Chile, the southern part of South America

 For 300 years, the Spanish tried to colonise the Araucanian people but failed. Araucanian people included the Mapuche, the Picunche, and the Huilliche, of modern-day Chile.

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The Spanish conquistadors began controlling much of South America, but the Mapuche resisted. After suffering in the harsh jungle landscape, Spain declared peace with Chile and its inhabitants. Following this, Chile became independent.

2. Persian-Roman Wars

• Duration: 92 B.C.-A.D. 629 (721 years)
• Combatants: Roman Republic/Empire and the Parthians and the Sassanids in Persia
• Killed: unknown
• Fought in: modern-day Iran

The Persian-Roman Wars lasted as long as two different Persian empires, the Parthians and the Sassanids. For much of the conflict, cities around the border were taken by one side, then recaptured by the other repeatedly.

Much of the damage was financial. Both sides spent so much preparing to fight each other that they were left vulnerable to other attackers.

1. Iberian Religious War

• Duration: 711-1492 (781 years)
• Combatants: Spanish Empire and the Moors
• Killed: 7 million
• Fought in: Spain

The longest war in history was the Iberian Religious War. The Catholic Spanish Empire and the Moors living in what is today Morocco and Algeria fought the war. The conflict, known as the “Reconquista,” lasted 781 years.

The battle ignited when the Moors crossed the Mediterranean Sea and claimed European territory. Spain took the encroachment by non-Christians as an offence and attacked the Moors. Though it was not part of the Crusades, the Catholic Church supported the war. In the 15th century, Moorish power and territory weakened. Subsequently, in 1492, the Spanish recaptured Granada and cemented their status in the region, thus ending the conflict.