20 Times Bitter Enemies Became Unlikely Allies

When Nazi Germany invaded the Soviet Union on June 22, 1941, British Prime Minister Winston Churchill suddenly found himself with a very unlikely ally: Soviet leader Joseph Stalin. This was quite the turnaround, as Churchill had supported Allied intervention against the Bolshevik regime during the Russian Civil War and spent the previous two decades denouncing communism as evil. He didn’t retract any of those criticisms when he broadcast his support for the Soviet Union that evening. Instead, defeating Nazi Germany gave Churchill and Stalin enough common ground to work together.

Before he became one of Genghis Khan’s generals, Jebe was an enemy warrior named Jirqo’adai. During Temüjin’s (the future Genghis Khan’s) 1201 campaign against the rival Tayichi’ud clan, Jirqo’adai fired an arrow that reportedly hit either Temüjin himself or his horse. After the battle, Temüjin asked who had fired the arrow, and Jirqo’adai confessed. Impressed by his honesty, Temüjin spared his life, promoted him to general, and renamed him Jebe, meaning “Arrow.” At least, that’s how the story is told in The Secret History of the Mongols.

Porus was the king of the Paurava kingdom in the Punjab region when he faced Alexander the Great’s invading army at the Battle of the Hydaspes in 326 BC, fighting with war elephants among his forces. Though severely wounded, Porus did not flee the battlefield. Impressed by his bravery, Alexander restored him as a local ruler, or satrap, made him an ally, and gave him an even larger territory in the Punjab. The arrangement also helped secure Alexander’s eastern frontier. Later Greek historians say Porus asked Alexander to treat him “like a king,” though that famous exchange is unconfirmed.

Ulysses S. Grant and James Longstreet had been close friends at West Point, but the American Civil War put them on opposite sides: Grant became a leading Union general, while Longstreet served as one of Confederate General Robert E. Lee’s senior commanders until Appomattox. After the war, Longstreet supported Republican-led Reconstruction, and when Grant became president, he appointed his old friend as customs collector in New Orleans and later as U.S. minister to the Ottoman Empire. Their friendship survived the war, but Lost Cause writers—who promoted a sympathetic version of the Confederate cause—never forgave Longstreet for his postwar choices.

John Adams and Thomas Jefferson worked together on the Declaration of Independence in 1776, long before they became bitter political rivals in the 1790s. After Jefferson defeated Adams in the presidential election of 1800, the two didn’t speak for more than a decade. In 1812, their mutual friend and fellow Founding Father Benjamin Rush convinced them to reconcile. In their final years, Adams and Jefferson exchanged 158 letters but never met again. Both died on July 4, 1826, the 50th anniversary of the Declaration. Adams’s last words reportedly mentioned Jefferson; he was unaware that his old friend had died earlier that same day.

The Visigoths, a Germanic people who had frequently fought and negotiated with the Roman Empire, famously sacked Rome in 410 AD. But a few decades later, the former enemies found themselves fighting on the same side. In 451, Roman general Flavius Aetius allied with the Visigoths under King Theodoric I, along with other foederati, or allied peoples who supplied troops to Rome. Together, they confronted Attila the Hun’s invasion of Gaul at the Battle of the Catalaunian Plains. Attila managed a well-organized withdrawal rather than being destroyed, while Theodoric was killed in the fighting. The alliance stopped that invasion of Gaul, though Attila returned to invade Italy the following year.

The relationship between the United States and Japan has gone through many stages: enemy, enemy under occupation, and sovereign treaty partner. After the atomic bombs, Japan surrendered, ending the brutal Pacific War between the US and Imperial Japan that had begun in 1941. During occupation under General MacArthur, Japan developed a pacifist constitution and Article 9 to renounce war. The two countries signed the U.S.-Japan Security Treaty and the San Francisco Peace Treaty on September 8, 1951.

After Charles V captured King Francis I at Pavia in 1525, Francis sought a counterweight to the dominant Habsburgs by dispatching envoys to Suleiman the Magnificent. Although they never met, the resulting Franco-Ottoman Alliance was formalized in 1536 and led to combined fleets in the Mediterranean that would continue to operate together for over two centuries. His rivals denounced this unprecedented entente, an alliance between Christian and Muslim powers, as the Sacrilegious Union.

The First Anglo-Powhatan War between English settlers in Virginia and the Powhatan peoples ended in a period of peace after Pocahontas married English tobacco planter John Rolfe in April 1614. If your knowledge of Pocahontas comes from Disney, her real marriage story was a lot more complicated. Pocahontas had been captured by the English in 1613 and converted to Christianity before the marriage, which took place with the consent of her father, Powhatan, the paramount chief of the Powhatan chiefdom. Jamestown records indicate that Powhatan didn’t attend the wedding himself but sent his brother Opitchapam. The resulting peace lasted for eight years, until Powhatan leader Opechancanough led an uprising against the English settlements in 1622.

Octavian and Mark Antony had fought each other after Julius Caesar’s assassination in 44 BC, including Octavian’s victory over Antony at Mutina in April 43 BC. But a common threat from the Senate led them to forge an unlikely alliance, despite their eventual falling-out before Actium in 31 BC. This pact between Antony, Octavian (only 19 at the time), and Lepidus, solidified by Lex Titia in November of 43 BC, created the so-called Second Triumvirate. Dividing Roman territories and ruthlessly targeting their opponents, the Second Triumvirate was an unstable and short-lived dictatorship.

Masinissa, a Numidian prince from North Africa, initially sided with Carthage during the Second Punic War and fought for it in Spain. However, when Carthage’s ally Syphax, another Numidian ruler, backed a rival claimant to Masinissa’s throne, Masinissa switched sides and joined Roman general Scipio Africanus in 206 BC. His support for Rome was mainly meant to ensure the survival of his own dynasty. In 202 BC, Masinissa’s cavalry helped defeat Carthaginian general Hannibal’s army at the Battle of Zama, and Rome rewarded him with a unified Numidian throne.

Under the Union of Lublin in 1569, Poland and Lithuania were combined into the Polish-Lithuanian Commonwealth. Catholic Poland and pagan Lithuania had warred over territory during the 13th and 14th centuries, but the hostile Teutonic Order caused Lithuania’s Grand Duke Jogaila to become Christian and marry Jadwiga of Poland under the Union of Krewo in 1385. In 1410, Lithuanians and Poles together defeated the Teutonic Knights at Tannenberg. However, Lithuania maintained its own laws, treasury, and army right up until that point.

On August 31, 1907, Britain and Russia signed the Anglo-Russian Convention, agreeing on spheres of influence for Persia, Afghanistan, and Tibet in an attempt to counter the threat of the Triple Alliance (Germany, Austria-Hungary, and Italy). The convention resolved imperial disputes rather than forming an alliance. The two countries had been at war with one another in the Crimean War (1853-1856) and had contended for control of Central Asia and Persia in a decades-long struggle known as the Great Game.

During their first encounter, two of Japan’s future great unifiers were enemies. Motoyasu, later known as Tokugawa Ieyasu, was under the control of the powerful Imagawa clan and was forced to fight against rival warlord Oda Nobunaga. But after Nobunaga defeated and killed Imagawa leader Yoshimoto at the Battle of Okehazama in 1560, Motoyasu was freed from Imagawa control. This led to Motoyasu and Nobunaga meeting at Kiyosu Castle in 1562 to form the Alliance of Kiyosu. During the volatile Sengoku period, when samurai alliances could fall apart at any moment, theirs endured for 20 years and was never once broken.

Athens and Sparta had previously been allies against Persia (480 BC) and foes in the Peloponnesian War (431–404 BC), which Sparta won. But when Thebes’s Epaminondas crushed Spartan power at Leuctra in 371 BC, the two old rivals formed a defensive coalition, fighting together at the second Battle of Mantinea in 362 BC.

A short-lived alliance of mutual defense was cemented in 1833 with the Treaty of Unkiar Skelessi. Sultan Mahmud II of the Ottoman Empire called on Russia for help against its vassal Muhammad Ali of Egypt who rose in rebellion in 1831. Russian troops landed at Unkiar Skelessi, which provided access to the Bosphorus, but not Constantinople. Russia and the Ottoman Empire had fought in twelve wars over a span of three centuries and would again in the Crimean War. The Treaty of Unkiar Skelessi was annulled in 1841.

The Prussian-Austrian Dual Alliance, established on October 7, 1879, and lasting through World War I, was a defensive pact against Russia. The alliance had its origins in Bismarck’s moderation towards Austria after Prussia defeated it at the Battle of Sadowa during the Seven Weeks’ War in 1866. Bismarck prevented Wilhelm I and Prussian generals from advancing into Vienna and annexing Austrian territory. Bismarck saved Austria’s honor although it lost the war.

After centuries of conflict, including the Hundred Years’ War and the Napoleonic Wars, Britain and France nearly came to blows again in Sudan during the Fashoda Incident of 1898. Just six years later, however, the longtime rivals signed the Entente Cordiale on April 8, 1904. Motivated partly by the growing power of Imperial Germany, they resolved colonial disputes regarding Morocco and Egypt. Although it was not a military alliance, the agreement marked the beginning of much closer cooperation between the two nations.

The United States and Britain have a long and checkered history, having fought each other twice: during the Revolutionary War (1775–1783) and the War of 1812. The Treaty of Ghent restored peace in 1814, although not an alliance, and the two countries continued to experience trade and border disputes for decades. Later, however, they reconciled during the Great Rapprochement (1895–1915), a period when arbitration helped settle disputes and laid the groundwork for their future alliance, including their eventual membership in the North Atlantic Treaty Organization (NATO), the military alliance founded in 1949.

At the end of World War II, the United States and Nazi Germany were enemies. After a partitioned Federal Republic of Germany (West Germany) emerged in May 1949, and with the aid of the US Marshall Plan and an escalating Cold War with the Soviet Union, West Germany’s integration into the Western bloc accelerated. A former enemy became a key ally within a mere decade after West Germany was rearmed and joined NATO on May 9, 1955, excluding the Communist East.

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