On July 20, 1942, the first detachment of the Women’s Army Auxiliary Corps — later known as WACs — began basic training in Iowa.
In 1944, an attempt by a group of German officials to assassinate Adolf Hitler with a bomb failed as the explosion only wounded the Nazi leader. Also: President Franklin D. Roosevelt was nominated for a fourth term of office at the Democratic convention.
In 1969, astronauts Neil Armstrong and Edwin “Buzz” Aldrin became the first men to walk on the moon.
In 1976, America’s Viking 1 robot spacecraft made a successful,first-ever landing on Mars.
In 1977, the U.N. Security Council voted to admit Vietnam to the world body.
In 2012, a mass shooting occurs at a movie theater in Aurora, a Denver suburb, killing 12 people—the youngest a 6-year-old girl—and injuring at least 70 others.
In 2015, the United States and Cuba restored full diplomatic relations after more than five decades of frosty relations rooted in the Cold War.