- The United States dropped an atomic bomb on Hiroshima. (1945) It was the first atomic bomb detonated in warfare. It killed 66,000 people instantly and a total of as many as 166,000 died over a period of months from the nuclear fallout. US President Harry S. Truman ordered the use of the first nuclear bomb, which the military referred to as "Little Boy." A second nuclear bomb, "Fat Man," was dropped on Nagasaki three days later on August 9.
- 50,000 people in Japan attended a memorial service mourning the Hiroshima anniversary. (1995) The service was held at the Hiroshima Peace Park, which was built on the spot where the bomb exploded. By this time, more than 192,000 people had died as a result of the bomb dropped on this day in 1945.
- The first person was executed in the electric chair. (1890) William Kemmler, convicted of murdering his lover Matilda Ziegler with an ax, was executed in New York at Auburn State Prison. The first shock was administered for 17 seconds but failed, leaving Kemmler alive. A second current of 1,030 volts administered for two minutes finally killed him.
- The World Wide Web became publicly available. (1991) Tim Berners-Lee invented the World Wide Web. On December 25, 1990, he successfully connected an http client with an Internet server. Less than a year later, on this day, the "WWW" was publicly accessible.
- The first woman swam across the English Channel. (1926) Gertrude Caroline Ederle, an American from New York State, was a competitive swimmer. She swam the channel in 14 hours and 31 minutes, two hours faster than the men's record.
- The world was sailed in the "wrong direction" for the first time. (1971) Chay Blyth from Britain sailed his yacht around the world from east to west, against the winds and currents. He completed the 30,000-mile (48,280-kilometer) journey in 292 days — also impressively setting the record for the fastest non-stop around-the-world sail.
- Harry Houdini remained sealed underwater for 91 minutes before escaping alive. (1926) Houdini was a famous Hungarian-American escape artist and magician. He famously escaped from all sorts of confinements, including handcuffs, prison cells, straight jackets, and even caskets after being buried alive.
- The first US military school was founded. (1819) Norwich University in Vermont educates about 2,000 students each year from 20 countries. 138 of the school's alumni have served as generals in the US military.
- Alice Ramsey and three of her friends were the first females to complete a transcontinental car trip. (1909) The journey began in Manhattan, New York, and ended in San Francisco, California. Of the 3,600-mile (5,794-kilometer) ride, only 152 miles (245 kilometers) were paved.
- American actress Lucille Ball was born. (1911) The comedienne, film star and television actress was possiblly best known for her I Love Lucy television show, which ran for nine seasons. Throughout her career, Ball won many awards, including four Emmy Awards, a Golden Globe and a Lifetime Achievement Award.
