From our Achilles tendon to our zeppelin airships, there are countless words in the dictionary that are named after characters, both real and invented, from throughout history and literature. But if legend is to be believed, easily one of the most unusual stories in the dictionary is that which lies behind both the name of a color called isabelline, and the European princess, Infanta Isabella, who inspired it.

Isabelline is the name of a pale, ruddy, yellowish-brown color. It’s unlikely to be a word you’ll have ever come across unless you’re an animal lover: it tends only to be used in the names of creatures like the Isabelline wheatear, an Asian songbird, and the Isabelline bear, a pale-colored subspecies of brown bear found in the Himalayas. As for its namesake, she too will be fairly unknown to most people: the Isabella in question is Isabella Clara Eugenia, the young daughter of King Phillip II of Spain and his third wife, Elisabeth of Valois, and an early 17th-century Habsburg ruler of the Spanish Netherlands.

Unless you’re an expert on the Habsburg monarchs of Europe, it’s unlikely that any of the names in that description will ring many bells—although Isabella’s father, Philip II, was for a time in the mid-1500s married to Mary I of England, the elder sister of Elizabeth I, making him a de facto king of Tudor England. This particular tale, however, takes place some three years after Philip’s own death, in 1601.

The dying King Philip II had made provisions in his will to bequeath rule of the Spanish Netherlands—a vast province of the northern Holy Roman Empire, comprising parts of modern-day France, Belgium, Luxembourg, Holland, and Germany—to Isabella, on the condition that she marry and thereby jointly rule with her cousin Albert VII, the Archduke of Austria. The pair duly married in 1599, and assumed joint control of the Spanish Netherlands at a particularly turbulent point in its history.

By the late 1500s, the Spanish Netherlands and its surrounding states had been embroiled in a bitter conflict that would eventually become known as the Eighty Years’ War, and go on to subsume much of western Europe. The Dutch, unhappy with Spain’s rule over the area (and the proliferation of Spanish Catholicism that went with it), had started to rebel against the Spanish control, and after an allied Dutch force retook the city of Groningen from the Spanish throne in 1568, war promptly broke out.

In response, Spain was quick to react and spent the next decade reasserting Spanish rule over much of the southern provinces of the Spanish Netherlands in a series of bloody battles and sieges. To survive the war without being subsumed entirely into the Spanish crown, the Dutch clearly needed allies and assistance—and in 1585 they got it.

Fearing the threat to English soil that a Spanish victory just across the English Channel would pose, Elizabeth I agreed to lend England’s support to the Dutch rebels. The Spanish, now essentially battling two powerful military forces at once, had a fight on their hands. As the conflict rumbled on, the Spanish forces became increasingly desperate to find some way of demonstrating and reasserting their power over the area; and eventually, all eyes fell on the only Dutch-controlled city remaining in the entire region: the Flemish city of Ostend.

The Spanish knew that retaking Ostend would prove an immense boost of morale to the flagging Spanish forces, and could help to tip the wartime balance against the English and Dutch. As a result, on July 5, 1601, Isabella’s husband, Albert of Austria, besieged the city with an army of 12,000 troops, easily outnumbering the 3,000 or so people (mainly impoverished fishermen and their families) who lived inside. Victory, it seemed, would come quickly.

Back home in Spain, Isabella was waiting patiently for news of her husband’s efforts in the war further north, and when news arrived that he was finally in a position to besiege and claim back control of Ostend, Isabella became convinced the conflict would soon be over. Indeed, she apparently became so sure of her husband’s imminent victory that she made an agreement with one of her handmaids (or, in other versions of the story, one of her husband’s counselors) to not change her undergarments until after Ostend had fallen under Spanish control. It seemed like an easy victory, both for Albert and for Isabella: surely a destitute fishing town of only a few thousand people could scarcely hold back the Spanish army? Within a few days, Isabella wagered, news would surely arrive of her husband’s victory.

In fact, she could scarcely have been more wrong.

Back in Ostend, Albert was facing a series of difficulties. Firstly, as the only Dutch controlled enclave still standing in the region, the Dutch forces had seen fit to bolster both Ostend’s defenses (which by upgrading its surrounding walls had been transformed into a series of battlements more befitting a military camp than a sleepy coastal resort) and its population (by ferrying more than 4,500 Dutch troops into the town). Not only that, but as a major fishing port, the north end of Ostend was open to the North Sea, and that vital channel enabled much needed military supplies, chiefly from across the Channel in England, to be ferried almost continually into the town.

Surrounding this maritime gateway, moreover, was a vast expanse of nearly impenetrable mudflats and quicksand, making this vital supply chain all but impossible to break from on land. Archduke Albert, ultimately, was with little option but to concentrate all of his Spanish forces onto the much more heavily-defended southern side of the town. Victory, if it were ever to come, was not going to come easy. The Siege of Ostend went on to last for some 1,173 days.

The Spanish finally proved victorious and retook the town in September 1604, but at an immense cost to their campaign. Thousands of Spanish troops had been killed. The Spanish treasury had been all but emptied. While having concentrated so fixedly on securing victory only in Ostend, in the meantime, the equally important Spanish-held port of Sluis, 20 miles to the east, had fallen to the Dutch and English forces. In the end, securing control of Ostend proved a hollow victory, and with few options remaining open to them, the Spanish called a halt to the war. An uneasy 12-year truce commenced.

In all this time, of course, Isabella reportedly remained true to her word and refused to change her underclothes until her husband had proved victorious. After more than one thousand days of brutal fighting and attrition, ultimately, her crisp, white undergarments were not quite as spotless as they had once been.

As a result—in perhaps one of the strangest word origin tales in the dictionary—Infanta Isabella ended up giving her name not to a pristine shade of white, but to a sandy, beige-like shade of yellow…