On this day in 1970, the Ohio National Guard, sent to Kent State University after disturbances in the city of Kent the weekend before, opened fire, killing four unarmed students and wounding nine others. The students were protesting the Cambodian Campaign of the United States and South Vietnam.
On this day in 1974, an all-female Japanese team reached the summit of Manaslu, becoming the first women to climb an 8,000-meter peak.
On this day in 1979, Margaret Thatcher became the first female Prime Minister of the United Kingdom.
On this day in 1990, Latvia proclaimed the renewal of its independence after the Soviet occupation.