Naval mines of various types have been used since the 16th century. However, it was not until World War I that they entered into wide use. Modern naval mines, which can be either automatic or remotely controlled, are equipped with sonar or magnetic sensors. They are laid on the surface of the sea or sometimes anchored below. For defensive purposes, mines are often placed in secretly charted locations near protected harbors by specially equipped vessels called minelayers. How are mines detected?
Back in the day
The Liberation of Paris is considered the last battle of the Normandy Campaign to free France from German occupation. In July, about a month after the Allied invasions of southern France and Normandy, Allied ground troops finally broke out of the beachheads and began a rapid advance across northern France. With help from the French resistance, Free French and US forces and liberated Paris in August. Why did the German military governor of Paris disobey Hitler's order to leave the city in ruins?
Born on a day like today
Gibson, a US tennis player, was the first African-American woman to compete on the world tennis tour. Though tennis had essentially been segregated until that time, she was finally given an opportunity to play at the US Championships in 1950. Having broken the color barrier, she went on to become the first black person to win Wimbledon. She was inducted into the International Tennis Hall of Fame in 1971. In 1964, Gibson became the first African-American player in what other sports organization?