1. The Ten Thousand

As chronicled in the historian Xenophon’s “Anabasis,” the “Ten Thousand” were a motley assortment of Greek warriors contracted by Cyrus the Younger to help oust his brother King Artaxerxes II from the Persian throne. In 401 B.C., the Hellenic soldiers-for-hire—many of them hardened veterans of the Peloponnesian War—fought alongside Cyrus and his rebel army in a clash with the King’s forces near Baghdad. While the Ten Thousand held their own in combat, Cyrus was killed in the battle, and the mercenaries’ generals were double-crossed and murdered while trying to negotiate a retreat.

Under pursuit from Artaxerxes II’s troops and hostile natives alike, the surviving members of the Ten Thousand were forced to band together and fight their way out of enemy territory. After electing Xenophon as one of their new leaders, the army of rogues embarked on a grueling nine-month odyssey that took them from the heart of Babylonia all the way to the Greek Black Sea port at Trapezus. Despite facing constant ambushes, punishing weather and famine, they arrived on friendly soil with nearly three-fourths of their numbers still intact. Xenophon’s account of the Ten Thousand’s fighting retreat has since become a classic tale of heroism, and even served as the inspiration for the 1979 cult film “The Warriors.”

2. The White Company

The White Company was one of the most infamous of the so-called “free companies”—bands of for-profit soldiers who conducted the lion’s share of warfare in 14th-century Italy. The unit first rose to prominence in the 1360s before falling under the command of Sir John Hawkwood, an Englishman who had been knighted for his service in the Hundred Years’ War. With Hawkwood at the helm, the White Company became known as one of the most elite mercenary armies in Italy. Its troops—a cultural hodgepodge of English, German, Breton and Hungarian adventurers—were renowned for their skill with the longbow and the lance, and they terrified opponents with their lighting-quick surprise attacks and willingness to do battle during harsh weather or even at night.

In an era when Italy was splintered between warring city-states and medieval lords, the men of the White Company made a killing by auctioning their services off to the highest bidder. Between 1363 and 1388, they fought both for and against the Pope, the city of Milan and the city of Florence, but they were rarely out of the field even during times of peace. In fact, when unemployed, the adventurers often kept their coffers full by launching raids on nearby villages and towns.

3. The Swiss Guard

Swiss Guard wait arrive of Italian Prime Minister Giorgia Meloni to have a meeting with Pope Francis at the Vatican on January 10, 2023
Massimo Valicchia / NurPhoto / Getty Images
Swiss Guards wait arrive of Italian Prime Minister Giorgia Meloni.

Today, the Swiss Guard is known as striped-uniformed protectors of the Pope in the Vatican, but their history stretches back to bands of mercenaries that flourished during the Renaissance. More than one million Swiss adventurers fought in Europe’s armies between the 15th and 19th centuries. These troops were among the first European soldiers to master the use of pikes and halberds against more heavily armored foes, and by the 1400s, their revolutionary tactics and sheer ruthlessness had earned them a reputation as the best contract troops money could buy. Swiss mercenaries often worked for the French, and they fought and died in large numbers during the French Revolution.

A small contingent of 150 Swiss soldiers of fortune began serving as papal bodyguards in 1506, and the unit endured as the official watchmen of the Vatican even after Switzerland banned its citizens from working as mercenaries. Still clad in their brightly colored Renaissance-era uniforms, the Swiss Guards of today are required to be Roman Catholics, stand at least 5 foot 6 inches tall and have a military background. Their role is often ceremonial, but in the past they have been required to fight to protect the pontiff. During one attack on Rome in 1527, nearly four-fifths of the Swiss Guard were slain while defending Pope Clement VII from capture.

4. The Flying Tigers

American pilots wearing parachute packs walk in front of their Flying Tigers fighter planes. The Flying Tigers flew in China with the Nationalist forces of Chiang Kai-Shek against the Japanese. They painted the planes with tiger shark faces to intimidate Japanese fliers. Ca. 1941
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Pilots walking past The Flying Tigers.

Officially known as the American Volunteer Group, the famed “Flying Tigers” were a three-squadron force of fighter pilots who fought with the Chinese against the Japanese during World War II. The unit was first organized in early 1941 in the months just before the bombing of Pearl Harbor. Eager to impede the Japanese takeover of China while still remaining neutral, President Franklin D. Roosevelt allowed former U.S. military officer Claire Chennault to quietly recruit fighter jocks from the ranks of the U.S. Army Air Force. The risks were high, but so was the pay: while most Air Force pilots received a salary of around $260 a month, Chennault’s mercenaries earned between $600 and $750, along with a $500 bonus for each Japanese aircraft they shot down.

Around one hundred American contract pilots arrived in Burma in mid-1941, where they were assigned to protect a crucial supply road from Japanese attacks. The “Flying Tigers”—famous for the iconic rows of shark teeth painted on the noses of their P-40 fighters—went on to rack up an unprecedented combat record. Despite flying slower, less maneuverable fighters than the enemy, the Americans downed 296 Japanese aircraft and destroyed more than 1,300 riverboats, all while only losing 69 planes and some two-dozen men. The group was officially disbanded in July 1942, but some of its members later rejoined their old units and served for the remainder of World War II.

5. The Catalan Grand Company

First organized in 1302 by the adventurer Roger de Flor, the Catalan Grand Company was primarily composed of rugged Spanish veterans of the War of the Sicilian Vespers in Italy. Left unemployed at the conflict’s end, De Flor and his mercenaries contracted themselves to the Byzantine Emperor Andronicus II, who brought them to the Eastern Mediterranean to fight off invading Ottoman Turks. The 6,500-strong Catalans succeeded in sweeping the Turks away from Constantinople, but their penchant for wanton sacking and looting also drew the ire of the Byzantines. In 1305, De Flor and some 1,300 of his men were ambushed and killed by another group of mercenaries in the Emperor’s employ.

Rather than disband, the surviving Catalans embarked on one of the bloodiest and most bewildering adventures in medieval military history. Following an abortive attempt to establish an outlaw state in Gallipoli, they marched to Greece and found work as muscle for the Duke of Athens. But when a dispute arose over back pay, the Catalans once again went to war with a former employer. After crushing the Greek armies and killing the Duke at 1311’s Battle of Kephissos, they found themselves the de facto lords of the Duchy of Athens. Amazingly, the mercenaries managed to consolidate their power and rule over large swaths of Greece for more than 75 years until an army from Florence finally defeated them in battle. The remnants of the Catalan Grand Company disbanded shortly thereafter.

6. The Varangian Guard

Scylitzes chronicle, Folio 43v. Theophilus with his bodyguard outside the church of Blachernae, dispensing justice to a widow who has approached him with a complaint. Two priests look on from the church door.
Werner Forman / Universal Images Group / Getty Images
Scylitzes chronicle.

The descendants of Norsemen who originally ventured south as pirates and traders, the Varangian Guard were a band of Viking mercenaries paid to serve as the personal bodyguard of the Byzantine Emperor. The Guard first took up their post in the late 10th century for Emperor Basil II, who preferred the axe-wielding barbarians to his more easily corruptible countrymen. The unit immediately proved useful in putting down a rebellion, and they went on to serve as the protectors of Constantinople for over two hundred years.

At first, the Varangian Guard was almost entirely composed of hard-fighting, hard-drinking Vikings, but by the late 11th century their ranks began to be filled out by Englishmen, Normans and Danes. Winning entrance into the unit was no easy task. Initiates had to demonstrate their prowess in battle and were forced to pay a small fortune in gold as an entrance fee. Still, the gifts showered on the Varangians ensured that its members left extremely wealthy, and some even went on to achieve positions of immense power. One of the most famous guardsmen was Harald Hardrada, who later claimed the throne of Norway.

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