Over the centuries, people have had some very good reasons to dress up like a member of the opposite sex. And I’m not talking about people who live this way out of personal preference, or those who dress up for theater and entertainment. Here are just five examples.

1. Cross-Dressing to Join the Army

Until recently, women have rarely been allowed to served as soldiers. So what was a gal to do if she wanted to serve her country? Naturally, disguise herself as a man and join the troops. At least 400 Civil War soldiers were women in drag. These included Union Army soldier “Frank Thompson” (also known as Sarah Edmonds—pictured above), whose small frame and feminine mannerisms (rather than causing suspicion) made her an ideal spy, as she could spy on the Confederates disguised as… a woman!

She wasn’t the first woman to don a male disguise and join the army, though. During the Revolutionary War, women fought as men on both sides. Hannah Snell, for example, joined the British army to find her husband, who had walked out on her to enlist. Once her true sex was discovery (thanks to a pesky groin injury), she became a national celebrity in Britain, and made a post-war career of performing in bars as the “Female Warrior.”

2. Cross-Dressing to Keep a Royal Family Together

With all the power play that went on in the court, the French royal family would go to great lengths to avoid sibling rivalry. In one of the more extreme cases, Philippe I, Duke of Orleans (1640-1701), was raised as a girl to discourage him from any political or military aspirations. This would make things easier for his brother, the future King Louis XIV. Philippe wore dresses and make-up, enjoyed traditionally feminine pursuits, and was even encouraged towards homosexuality.

A girly man he might have been, but he married twice and even had a mistress. When necessary, he could even lead an army into battle. (This is the nation, after all, that gave us that famous cross-dresser Joan of Arc.) A brave commander, he would go into battle wearing high heels, plenty of jewelery and a long, perfumed wig. One of his wives claimed that Philippe’s biggest fear when going into battle was not bullets, but the possibility of looking a mess. He avoided gunpowder (with the black smoke stains) and didn’t wear a hat, to avoid ruining his hair.

3. Cross-Dressing to Win Olympic Glory

Dressing in drag has been part of the Olympics (on and off) since ancient times, when women were banned from the bulk of the Games. The Greek historian Pausanias of Damascus said that if a spectator was uncovered as a woman in male disguise, she was duly escorted off the premises… and thrown off a cliff. In later Games, the athletes started performing naked, and the crowd was also ordered to disrobe. It has been suggested that this was to ensure that they were all men.

In the modern Olympics, there has been less disrobing—and not much cross-dressing, either. Gender tests have been normal procedure since 1966 (for athletes, not spectators), so they couldn’t really get away with it. Before that time, one of the strangest—and most controversial—cases was Polish sprinter Stanislawa Walasiewicz (aka Stella Walsh), who set 11 world records in her career, winning the 100-meter Olympic finals in 1932 with what one official described as “long man-like strides.” After she died in 1980, however, it was revealed that she had indeed been a man. So had he deliberately set out to fool everyone all that time? Perhaps not. Walasiewicz had a condition known as “mosaicism,” which gave her male chromosomes. Did they give her an unfair advantage? It is difficult to say. However, if she tried out for the Olympics today, she would not be allowed to compete as a woman.

4. Cross-Dressing to Commit Espionage

There have been many instances of cross-dressing spies (including Sarah Edmonds, mentioned above), but one of the most impressive deceptions in history was carried out by Shi Pei-Pu, a singer with the Beijing Opera (in which, traditionally, all roles are played by men). In 1964 he disguised himself as a woman to seduce Bernard Boursicot, an attache in the French Foreign Service. Their affair lasted 20 years (on and off), during which Boursicot passed several official documents to Shi, believing that “her” safety was at risk if he didn’t participate. After they were separated in 1965, Shi came back into Boursicot’s life by claiming to be pregnant, and even revealed a baby boy. They later lived as a family. The happy couple was eventually arrested for espionage in 1983, and Shi’s secret was revealed, Crying Game style, to the stunned Boursicot.

But how did they have this romance for so long without Bousicot knowing the truth? Officially, they rarely made love, and always did it hurriedly and in darkness – something that Boursicot always ascribed to Shi’s demure Chinese upbringing. One theory, however, is that he always knew the truth, but played dumb to conceal his homosexuality. (He later came out.)

The affair was the basis for the play M. Butterfly. It was filmed in 1993, starring Jeremy Irons and former Beijing Opera player John Lone (better known for the title role of The Last Emperor).

5. Cross-Dressing to Get Rowdy

Hindu women in India have traditionally lived inhibited lives, tending the home for their families. But on one night each year, in the city of Jodhpur, they come to life at the so-called “Festival of Fun.” Dressed as noblemen, complete with turbans and large fake mustaches, they walk the streets in gangs, brandishing sticks, beating any males who are foolish enough to be out there. The festival celebrates an ancient domestic dispute between the Hindu god Shiva and his wife Ganwar. While the women sing devotional songs asking the goddess to return to her husband, they also take this as their only opportunity to do what they long to do all year: behave like men. Their husbands, respecting the tradition, let them go wild. It sounds like fun (as long as you’re not a clueless male who forgot to stay at home that night), but one thing concerns me: if a woman’s disguise is especially good, does she risk being mistaken for a man and beaten up by her friends?

Mark Juddery is a writer and historian based in Australia. See what else he’s written at markjuddery.com.