Hattie McDaniel’s Oscar, Biden’s big win and more historic moments that happened on a Leap Day

Every four years, the shortest month of the year gets just a tad bit longer.

The idea for adding a day to the year to account for Earth's imperfect rotation around the Sun has been around for millennia. Leap Days themselves, meanwhile, have actually been tacked onto every fourth February ever since the Gregorian calendar was reformed in 1582.

So, while Feb. 29 doesn't come around all that often, they've added up over the centuries. What that means is, while there may be only 25 or so Leap Days each century, plenty of notable events have just so happened to take place on the infrequent date of Feb. 29.

Here's a look at some historical events that have occurred on a Leap Day.

How often is leap year? Here's the next leap day after 2024 and when we'll (eventually) skip one

Feb. 29, 1692: Arrest warrants signal start of Salem witch trials

The 17th century witchcraft hysteria that gripped colonial America began on a Leap Day with the issuance of arrest warrants for three women: Sarah Good, Sarah Osborne and Tituba.

The women's arrests in 1692 for suspected witchcraft were the first of hundreds that led to 19 people – most of them women – being executed by hanging. One other man, Giles Corey, was crushed to death by rocks when he refused to to enter a plea, while at least five others died in jail.

The ugly chapter of American history ultimately became known as the Salem witch trials, and remains an enduring part of the legacy and identity of the New England area about 20 miles northeast of Boston.

Feb. 29, 1940: First Black actor wins an Oscar

Hattie McDaniel became the first Black person to win an Academy Award during a ceremony held on Leap Day in 1940. Even today, her win for best supporting actress Oscar for "Gone With the Wind" is one of the most important moments in Oscar history.

But it was also marred by the institutionalized racism that plagued the United States.

That year's Oscars were held in a "no blacks" hotel and after accepting her award, McDaniel, who died in 1952, was forced to sit at a segregated table, away from the rest of the "Gone With the Wind" cast.

McDaniel died in 1952 of breast cancer at the age of 59. In 2006, the U.S. Postal Service issued a commemorative stamp honoring the Oscar winner.

Feb. 29, 1996: Siege of Sarajevo comes to an end

For nearly four years, the bloody breakup of Yugoslavia led to a prolonged siege and assault on Sarajevo.

Cut off the from outside world, about 350,000 people were trapped for 1,425 days in the capital city of Bosnia and Herzogovina while Bosnian forces subjected them to daily shelling and sniper attacks. A vast area of Europe was plunged into the conflit, which was marked by Ethnic cleansing and war crimes as rival ethnic, religious and political groups clashed.

It wasn't until after the war's violent climax in the 1995 Srebrenica massacre that the siege finally came to end a year later on Feb. 29, 1996.

Even today, it still marks the longest siege of a capital city in the history of modern warfare, according to History.com.

Feb. 29, 2020: Joe Biden wins the South Carolina Primary

Four years ago today, President Joe Biden won the South Carolina Primary. Many pundits marked the moment as a turning point for his campaign, which would end with him as the Democratic nominee.

Biden would of course go on to defeat President Donald Trump in 2020, and now the pair appear destined for a rematch in November.

Eric Lagatta covers breaking and trending news for USA TODAY. Reach him at elagatta@gannett.com

This article originally appeared on USA TODAY: On this day in history Feb. 29: Events that happened on a Leap Day