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Caesar's Civil War (49–45 BCE) -

Sometimes referred to as the Roman Civil War, this was one of the last politico-military conflicts of the Roman Republic before its reorganization into the Roman Empire. It was fought between two factions led by Gaius Julius Caesar and Gnaeus Pompeius Magnus (Pompey), respectively. It ended with a Caesarian victory and left over 15,000 Pompeians dead, while Caesar lost only 200.

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Sasanian Civil War (589–591 CE) -

Dissent among nobles towards the rule of Hormizd IV, the Sasanian King of Kings of Iran, eventually led to the Sasanian Civil War. The feeling was mutual: Hormizd IV disliked and distrusted the nobility and in particular the Mihranid usurper Bahram Chobin. The war ended with the overthrow of Chobin and the restoration of the Sasanian family as the rulers of Iran.

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Danish civil wars (1131–1157) -

The long period of sporadic civil wars that the Kingdom of Denmark suffered from 1131 to 1157 claimed numerous lives and the deaths of seven kings. A war of succession fought from 1146 to 1157 finally ended hostilities with Valdemar I, having outlived all his rival pretenders, becoming the sole King of Denmark.

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Armagnac–Burgundian Civil War (1407–1435) -

The Armagnac-Burgundian Civil War was a conflict that took place between two cadet branches of the French royal family, the House of Orléans (Armagnacs) and the House of Burgundy (Burgundians), and in turn was part of the Hundred Years' War. It began with the assassination of Louis I, Duke of Orléans in Paris in November 1407. Another high-profile victim of the war was John the Fearless, Duke of Burgundy.

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Wars of the Roses (1455–1487) -

The Wars of the Roses were a series of civil wars fought over the throne of England between supporters of the House of Lancaster, the Lancastrians, and supporters of the House of York, the Yorkists. Differences were settled at the Battle of Bosworth Field in 1485 when Henry Tudor of the House of Lancaster defeated King Richard III to ascend the throne as King Henry VII.

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Ōnin War (1467–1477) -

A dispute between a high official, Hosokawa Katsumoto, and a regional lord, Yamana Sōzen, escalated into a nationwide civil war largely fought within the imperial capital of Kyoto, almost completely destroyed by combatants during repeated engagements. The Ōnin War ended without a clear victory or defeat and remains one of the largest civil wars in Japanese history.

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Inca Civil War (1529–1532) -

The Inca Civil War, also known as the Inca Dynastic War, was fought between half-brothers Huáscar and Atahualpa over succession to the throne of the Inca Empire after the death of their father, Huayna Capac. Atahualpa (pictured) prevailed to become emperor, but his reign was short-lived. Atahualpa was hanged by Francisco Pizarro as the Spanish conquistadors sacked the city of Cajamarca.

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French Wars of Religion (1562–1598) -

The French Wars of Religion were a series of eight conflicts between Protestant (Huguenots) and Catholic factions in France lasting 36 years. Between two and four million people died from violence, famine, or disease directly caused by the conflict before Protestant King Henry IV  converting to Catholicism in the interests of peace.

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English Civil War (1642–1651) -

The English Civil War actually refers to a number of separate conflicts fought across the Kingdom of England from 1642 to 1651. Royalists and Parliamentarians clashed on numerous occasions, famously at the Battle of Naseby in 1645. The war was eventually won by Cromwell's roundheads, after which King Charles I lost his head on the scaffold.

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Choctaw Civil War (1747–1750) -

The little-studied Choctaw Civil War was a period of economic and social unrest among the Choctaw people that degenerated into a civil war. Hostilities broke out between rival factions within the Choctaw over what the tribes' trade relations with British and French colonists should be. Ultimately, relations with the French were strengthened, while trade with the British was severed.

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Taiping Rebellion (1850–1864) -

The Taiping Rebellion remains one of history's costliest civil wars in terms of human lives. The conflict resulted in an estimated 20 to 30 million deaths, approximately one-tenth to one-twentieth of China's population at the time.

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American Civil War (1861–1865) -

One of the most famous civil wars in history, the American Civil War was essentially the culmination of the struggle between the advocates and opponents of slavery that dated from the founding of the United States. The Union victory over the Confederacy forever changed the makeup of the nation. In total, the war left between 620,000 and 750,000 soldiers dead.

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Chilean Civil War (1891) -

In an armed struggle that dramatically altered the nature of Chilean political life, the country's civil war of 1891 saw forces supporting congress and forces supporting the president, José Manuel Balmaceda, clash by way of a confrontation between the Chilean Army and the Chilean Navy, which sided with the president and congress, respectively. The conflict ended with the defeat of the Chilean Army and the presidential forces, with President Balmaceda taking his own life as a consequence.

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Russian Civil War (1917–1923) -

The Russian Civil War was sparked by the October Revolution, itself a key moment in the larger Russian Revolution. The civil war was fought mainly between the "Reds," led by the Bolsheviks, and the "Whites," a politically-diverse coalition of anti-Bolsheviks. The conflict brought death and suffering to millions of people regardless of their political orientation. Its finale also marked the end of the Russian Revolution, which saw the country abolish its monarchy and adopt a socialist form of government.

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Finnish Civil War (1918) -

The little-known Finnish Civil War took place from January 27 to May 15, 1918, and was fought between White Finland and the Finnish Socialist Workers' Republic (Red Finland). It resulted in a Finnish Whites victory—effectively a win for independence from the Russian Empire.

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Irish Civil War (1922–1923) -

The Irish Civil War was a bitter conflict between those who supported the Anglo-Irish Treaty (1921), which ended the Irish War of Independence, and those who opposed the treaty, which created an independent Irish Free State within the British Empire.

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Chinese Civil War (1927–1949) -

The Chinese Civil War, fought intermittently between Chinese nationalists and the forces of the Chinese Communist Party, ended when the nationalists under Chiang Kai-shek evacuated to the island of Taiwan to carry on as the Republic of China, while the communists under Mao Tse-tung established the People's Republic of China on the mainland. Hundreds of thousands of combatants and civilians died over a 22-year period.

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Constitutionalist Revolution (1932) -

Sometimes also referred to as the Paulista War or Brazilian Civil War, the Constitutionalist Revolution pitched the population of the Brazilian state of São Paulo against the federal government of Getúlio Vargas. The war's causes lay in the traditional balance of power between the country's two largest states, which broke down as a result of economic depression. Though the federalists held the initiative at first, most of the other states eventually came to São Paulo's side, resulting in a rebel victory. The Old Republic was overthrown and a Constitutional Assembly elected.

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Spanish Civil War (1936–1939) -

A bloody three-year conflict between Nationalists and Republicans, the Spanish Civil War claimed the lives of approximately 450,000 people from both sides of the divide. It ended with a victory for Francisco Franco, who ruled Spain until his death in 1975.

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Greek Civil War (1946–1949) -

The Greek Civil War actually erupted in December 1944, pulling British forces into combat in Athens. Britain formally withdrew from Greece in early 1947, but by then a full scale communist-dominated uprising against the established government of the Kingdom of Greece was taking place. The government ultimately prevailed, though 158,000 died in the fighting.

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Nigerian Civil War (1967–1970) -

Fought between Nigeria and the Republic of Biafra, a secessionist state which had declared its independence from Nigeria in 1967, what became known as the Nigerian Civil War was more about the federal government reclaiming vital coastal oil facilities than safeguarding the welfare of the Igbo people, the ethnic group Biafra represented. Around 30,000 Biafrans were killed in actual fighting: a further two million died of starvation and disease.

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Cambodian Civil War (1967–1975) -

Played out against the backdrop of the Vietnam War, the Cambodian Civil War was fought between the forces of the Communist Party of Kampuchea (known as the Khmer Rouge, supported by North Vietnam and the Viet Cong) against the government forces of the Kingdom of Cambodia. The conflict led to the Cambodian genocide, one of the bloodiest in history.

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Ethiopian Civil War (1974–1991) -

The Ethiopian Civil War began in September 1974 when the Marxist Derg staged a coup d'état against Emperor Haile Selassie. It lasted until the Ethiopian People's Revolutionary Democratic Front, a coalition of rebel groups, overthrew the government. Half a million were killed fighting, and another 1.2 million died from famine.

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Lebanese Civil War (1975–1990) -

Breaking out in 1975, the Lebanese Civil War was a multifaceted armed conflict that ripped the country apart and claimed an estimated 150,000 lives. The fighting also led to an exodus of one million people from Lebanon.

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Angolan Civil War (1975–2002) -

The impending independence of Angola from Portugal in 1975 precipitated a civil war that, while a power struggle between two former anti-colonial guerrilla movements, also grew into a Cold War competition between the Soviet Union and the United States. When the war ended, an estimated 500,000 to 800,000 Angolans had been killed.

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First Liberian Civil War (1989–1997) -

Eight years of violence during the First Liberian Civil War, which saw the overthrow of President Samuel Doe by the National Patriotic Front of Liberia led by Charles Taylor, claimed the lives of at least 200,000, including civilians. The Second Liberian Civil War lasted from 1999 to 2003 and was equally brutal.

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Rwandan Civil War (1990−1994) -

One of the most savage civil wars of recent history, the fighting that took place between the Rwandan Armed Forces, representing the country's government, and the rebel Rwandan Patriotic Front (RPF) during the Rwandan Civil War arose from the long-running dispute between the Hutu and Tutsi groups within the Rwandan population. Over the course of about a hundred days, between 500,000 and one million Tutsi and moderate Hutu were killed before the RPF claimed a hollow victory.

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Sierra Leone Civil War (1991–2002) -

The Sierra Leone Civil War began when the Revolutionary United Front (RUF) under Foday Sankoh, with support of Liberian rebel leader Charles Taylor and his group the National Patriotic Front of Liberia, attempted to overthrow the government of President Joseph Momah. The war was especially brutal as both sides were often funded by "blood diamonds" mined using slave labor.

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First Congo War (1996–1997) -

The First Congo War is remembered as being Africa's First World War for its ceaseless killing and dying that seemed to achieve nothing. It took place mostly in Zaire (which was renamed the Democratic Republic of the Congo in the process), with major spillovers into Sudan and Uganda. The civil conflict culminated in a foreign invasion that replaced Zairean president Mobutu Sese Seko (pictured) with the rebel leader Laurent-Désiré Kabila. The new incumbent's unstable government set the stage for the Second Congo War of 1998–2003.

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Yemeni Civil War (2014–present) -

The Yemeni Civil War began in 2014 when Houthi forces took over the capital city of Sanaa, which was followed by a rapid Houthi takeover of the government. The Houthis are presently embroiled in further conflict surrounding the targeting of international shipping in the Red Sea.

Sources: (The National WWII Museum) (United States Department of State) 

See also: Who are the Houthis, and why are they being attacked?

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