Alexander the Great’s Sister the Mermaid

Today, let’s discuss a great king’s daughter born on an auspicious day, whose half brother would go on to conquer much of the known world, and who would herself marry a great king — all before becoming a mermaid.

Thessalonike was a very well connected woman in the ancient world of Macedonia. While her culture limited her role to relationships with powerful men, she went on to have legacy that long outlived her.

But this legacy is of the strangest kind. For hundreds of years after her death, she was feared by Greek sailors as a powerful mermaid capable of transforming into a dread gorgon if her questions were not met with the correct answer.

This odd story from the ancient world is a combination of big history, personal life, classical mythology, and the superstitions of sailors. It highlights the worldview and thought processes of a great civilization and the role of celebrity in it. It is the story of Thessalonike, the mermaid.

The Life and Times of Thessalonike

She was born in the years around 350 BCE. Her royal family was headed by her father King Philip II of Macedonia. At the time of her birth, Philip was engaged in the Third Sacred War, in which the forces of Thebes and Macedonia were set against the Phocians.

On the very day of her birth, Philip found victory in the Battle of Crocus at Thessaly. The victory was definitive and devastating — the day was the single bloodiest battle in the history of ancient Greece. 6,000 Phocians lay dead at the end of the day with 3,000 more captured as prisoners of war. The leader of the opposing army was drowned, preventing him from an honorable burial.

This gruesome scene led to Philip being crowned the archon of Thessaly, and it secured Macedonia as the center of Greek politics.

To commemorate the connection between his daughter’s birth and the greatest victory of his career, Philip named his daughter Thessalonike — meaning victory at Thessaly.

Thessalonike’s mother Nicesipolis died soon after birth, and so the baby girl was sent to be raised by her stepmother Olympias. Olympias ensured that the adorable Thessalonike would be raised as her own flesh and blood daughter, keeping her in the queen’s quarters.

Olympias had other children, most notably Alexander (yes, that Alexander, as in, the Great). But while Thessalonike was a young girl, her step brother was in the Garden of Midas under the tutelage of Aristotle. And by the time she was six or seven, Alexander was already beginning his great Persian campaign. She was a youthful 21 years old when her step brother died at the palace of Nebuchadnezzar II.

Thessalonike stayed close to the palace through her life, and she huddled in the same queen’s quarters she was raised in when the conquering king Cassander bore down on the city. A power struggle had erupted after Alexander’s death. Cassander was looking for victory, and he spared Olympias and took Thessalonike as his wife, connecting him to the late king’s bloodline. He would go on to win the throne and become leader of Macedonia.

Thessalonike bore Cassander three children: Philip, Antipater, and Alexander, respectively. After their father’s death, Philip became leader as the eldest son. His mother insisted, however, that he share power with his youngest brother Alexander. This enraged the middle child Antipater who felt skipped over.

It was in 295 BCE that Antipater murdered his own mother for her partial treatment.

Thessalonike lived her entire life in the center of Greek power. She was a daughter, sister, wife, and mother to kings. Even still, the sexist society she found herself in gave her little agency. And despite her lifelong proximity to the throne, relatively little is known about her.

Her tragic death at the hands of her own son also shows the mixed blessing of her connection to the throne. But nevertheless, it was after death that the legend of Thessalonike began, and it would live on in one form or another until the present day.

The Legend of Thessalonike

The Aegean Sea lies between Greece and modern day Turkey. It was a key segment of the Mediteranean in ancient Greece, and sailors frequented its waters for commercial and military pursuits.

At some point, we do not exactly know when, these sailors began returning to their port towns with the strangest stories, stories that lasted for centuries.

They reported sightings of Thessalonike, thought to be long dead, swimming in the Aegean. According to legend, her brother Alexander had, during his campaigns, sought the Fountain of Immortality.

While the great king never found the fountain, he did obtain a small flask of water drawn from it. He used this water to bathe his sister’s hair.

When Alexander died, Thessalonike went mad with grief. She plunged into the Aegean Sea to drown herself, so inconsolable she was at the passing of her beloved brother. It was then that she discovered the full power of the magical water from Alexander’s flask. Instead of drowning, Thessalonike turned into a mermaid.

The sailors telling this tale would also include a warning to any unlucky seaman who caught sight of her. For she would inevitably confront them and ask them the question, “Is Alexander the king alive?” And the sailor must, if he valued his life at all, reply, “He lives and reigns and conquers the world.”

If the correct answer was given, Thessalonike would trouble the sailors no more and quiet the waters for the rest of their journey. But if any other answer was given, the mermaid would transform into a hideous gorgon — a terrifying creature with snakes for hair and whose gaze turned people to stone.

It was believed best, then, to remember the correct answer.

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