1775: The Battles of Lexington and Concord, the first military engagements of the American Revolutionary War including "the shot heard round the world," were fought. 1831: German physicist Johann Gottlieb Friedrich von Bohnenberger, inventor of the gyroscope, died. 1877: Ole Evinrude, of outboard motor fame, was born. 1906: Nobel laureate Pierre Curie, who along with his wife, Marie, discovered spontaneous radioactivity in radium and polonium, died. 1948: The ABC television network went on the air for the first time. 1961: My lovely wife, Melanie, was born - Happy Birthday! 1975: India launched its first satellite, Aryabhata, with aid from the USSR. 1989: Pro-Democracy demonstrations began in Beijing's Tiananmen Square. 1993: Attorney General Janet Reno ordered the raid on the Branch-Davidian compound in Waco, TX, that resulted in the death of 86 men, women and children. 1995: A truck bomb, driven by Timothy McVeigh and an unidentified passenger, exploded outside the Alfred P. Murrah Federal Building in Oklahoma City, killing 168 people, and injuring 500.