Catherine the Great moved to a foreign land as a teenager and became one of the most important leaders in its history. During her 34-year reign, she transformed Russia’s culture while expanding its borders. Here's what you need to know about the unlikely ruler, who is the subject of not one, but two new series: HBO's Catherine the Great, which debuted in late 2019, and Hulu's The Great, which is streaming on Hulu now.

1. Catherine the Great's name wasn't Catherine.

The woman who would become Catherine the Great was born Sophie Friederike Auguste von Anhalt-Zerbst on April 21, 1729 (Julian Calendar) in Stettin, Prussia (now Szczecin, Poland). She was the daughter of Christian August, a minor German prince and general in the Prussian army, and Princess Johanna Elisabeth, who had connections to the Russian royal family.

Despite being a princess herself, young Sophie wasn’t exactly a top-tier member of the European nobility. But thanks to her mother’s campaigning, she was chosen to marry Karl Peter Ulrich (later known as Tsar Peter III), heir to the Russian throne. The couple wed on August 21, 1745. Sophie converted to Russian Orthodoxy—despite her Lutheran father’s objections—and took on a new Russian name: Ekaterina, or “Catherine.” Her official title would be Empress Catherine II (Peter the Great's second wife had been Empress Catherine I).

2. Catherine the Great's marriage to Peter the III was rocky.

G.A. Kachalov, Public Domain // Wikimedia Commons

Catherine and Peter were an ill-matched pair: Catherine was bright and ambitious whereas Peter, according to Britannica, was "mentally feeble." Catherine didn’t like him: “Peter III had no greater enemy than himself; all his actions bordered on insanity,” she wrote in 1789. Her memoirs portray the Tsar as a drunk, a simpleton, and somebody who “took pleasure in beating men and animals.” Whether these statements are accurate or not, Catherine and her spouse were clearly unhappy, and they both had extramarital affairs. Catherine had at least three affairs, and hinted that none of her children were her husband's.

3. Catherine the Great overthrew Peter the III so that she could rule.

Peter III assumed the throne on January 5, 1762, and was immediately unpopular. He enraged the military by pulling out of the Seven Years’ War and making big concessions to Russia’s adversaries in the process.

Eventually, Catherine believed that Peter was going to divorce her—so she worked with her lover, Grigory Grigoryevich Orlov, and her other allies to overthrow him and take the throne for herself. In July 1762, just six months after he took the throne, Peter III was deposed in a coup d'état. Eight days later, he was killed while in the custody of one of Catherine's co-conspirators.

With Peter out of the picture, Catherine became the new empress of Russia. She was formally crowned on September 22, 1762. She never married again, and took numerous lovers during her long reign.

4. Voltaire was basically Catherine the Great's pen pal.

Catherine, a bibliophile, built up a collection of 44,000 books. Early in her reign, she began a correspondence with one of her favorite authors: The great Enlightenment philosopher Voltaire. Russia fascinated Voltaire, who had written a biography of Peter the Great. Catherine would never get the chance to meet him in person, but through these letters, she and Voltaire discussed everything from disease prevention to Catherine's love of English gardens.

5. Catherine the Great annexed Crimea.

Russian interest in the Crimean Peninsula long predates Vladimir Putin. After the Russo-Turkish War of 1768 to 1774, Catherine seized the landmass, thus strengthening Russia’s presence on the Black Sea. And her conquests didn’t end there. Over 200,000 square miles of new territory was added to the Russian empire during Catherine’s rule. Much of it was acquired when the once-independent nation of Poland was divided between Austria, Prussia, and Russia. Tsarina Catherine’s slice contained portions of modern-day Lithuania, Latvia, and Ukraine.

6. Great Britain asked for Catherine the Great's help when the Revolutionary War broke out.

In 1775, the Earl of Dartmouth approached Catherine with a request for 20,000 Russian troops to help Britain put down the colonial rebellion in America. She refused. As the war continued, British diplomats kept trying to establish an alliance with Russia, hoping that the Empress would either send military aid or, failing that, pressure France into abandoning the American cause. Catherine did neither. However, out of concern for Russian shipping interests in the Atlantic (and elsewhere), she did attempt to mediate an end to the violence between Britain and its rebellious colonies in 1780.

7. Alaska was colonized on Catherine the Great's watch.

Russian explorers had been visiting Alaska since 1741, but the empire didn’t set up its first permanent colony there until 1784, when merchant Grigory Shelikhov sailed to Kodiak Island and established the Three Saints Bay Colony. Later, in 1788, he visited Catherine in St. Petersburg and asked if she’d give his company a monopoly over the area’s lucrative fur trade. She denied his request, but thanked the explorer for “[discovering] new lands and peoples for the benefit of the state.” Russia’s colonial presence in North America would continue long after Catherine’s death—and it wasn’t limited to Alaska.

8. Catherine the Great embraced inoculation.

Thomas Dimsdale, an English physician, built upon an existing technique for immunizing people to smallpox. The technique involved finding a carrier of the ailment, then taking a blade dipped in a very, very small amount of "the unripe, crude or watery matter" from that person's pustules and injecting it into the patient’s body. In 18th century Russia, smallpox claimed millions of lives, so Catherine was eager to see if Dimsdale’s strategy worked. At her invitation, he came to Russia and quietly inoculated the empress. The procedure was a success, and with the Tsarina’s encouragement, Dimsdale inoculated about 150 members of the nobility. Before the end of the century, approximately 2 million Russians had received smallpox inoculations.

9. A rebel claimed to be Catherine the Great's dead husband.

Catherine’s Enlightenment-fueled beliefs didn't lead to the demise of serfdom. According to Marc Raeff in his book Catherine the Great: A Profile, "During her reign it was possible to buy and sell serfs with or without land, buy whole families or individuals, transact sales on the estate or marketplace; contemporaries termed all this ‘veritable slavery.'”

The unjust arrangement triggered 160 documented peasant uprisings in the first 10 years of Catherine’s reign. The best known of them was Pugachev’s Rebellion (1773-1775) [PDF], which was organized by Yemelyan Pugachev, a veteran of the Russo-Turkish wars. To win support, he introduced himself as Catherine’s deposed and deceased spouse, Peter III (even though Pugachev looked nothing like Peter). Pugachev and his followers enjoyed some big military victories early on, but after a crushing defeat in August 1774, their revolution fell apart. Pugachev was captured and executed in Moscow on January 10, 1775.

10. Catherine the Great's art collection was the basis of St. Petersburg's State Hermitage Museum.

In 1764, Catherine purchased a set of 225 paintings—including works by Rembrandt and Frans Hals—from a Berlin dealer, and founded the Hermitage with those works. Catherine went on to buy or commission thousands of additional pieces for her budding museum. Today, the State Hermitage Museum has more than 3 million items in its collections.

11. Catherine the Great was Russia's longest-serving female leader.

Thirty-four years after assuming the throne, Catherine passed away on November 6, 1796. The monarch was succeeded by her son, Tsar Paul I.

12. Wild rumors flew after Catherine the Great's death—including that one about the horse.

A lot of rumors sprung up in the wake of Catherin's death. One said that she had died while on the toilet, while another—the most persistent tale, and a completely unfounded one—claimed that Catherine the Great was crushed to death while attempting to have sex with a stallion. Where exactly the story came from is unknown; an autopsy determined that the empress had actually died of a cerebral stroke.