On April 7

A hijacker deliberately drove a truck into crowds along Drottninggatan in Stockholm, Sweden, killing five people.

NASA's 2001 Mars Odyssey (artist's conception pictured), the longest-surviving continually active spacecraft in orbit around a planet other than Earth, launched from Cape Canaveral.

First Chechen War: Russian paramilitary troops began a massacre of hundreds of civilians in Samashki, Chechnya.

A FedEx employee tried to hijack Federal Express Flight 705 in a failed suicide attempt.

Rwandan Civil War: The Rwandan genocide began a few hours after the assassination of President Juvénal Habyarimana, with hundreds of thousands killed in the following 100 days.

Uganda–Tanzania War: Tanzanian forces defeated Ugandan troops and their Libyan allies at the Battle of Entebbe, opening the way for an advance on the Ugandan capital, Kampala.

Communist forces overran the South Vietnamese town of Lộc Ninh.

American Presbyterian minister Bruce W. Klunder was killed by a bulldozer while protesting the construction of a segregated school in Cleveland, Ohio.

The Rodgers and Hammerstein musical South Pacific, based on Tales of the South Pacific by James Michener, opened on Broadway.

The United Nations established the World Health Organization to act as a coordinating authority on international public health.

World War II: U.S. forces sank the Japanese battleship Yamato during Operation Kikusui I in the East China Sea.

Italian dictator Benito Mussolini survived an assassination attempt by Irishwoman Violet Gibson.

An Arctic expedition led by Norwegian explorer Fridtjof Nansen (pictured) reached 86°13.6′N, almost three degrees beyond the previous Farthest North latitude.

American Civil War: Union forces defeated Confederate troops at the Battle of Shiloh, at the time the bloodiest battle in U.S. history, in Hardin County, Tennessee.

Pedro II became emperor of the Empire of Brazil.

After a conclave lasting eighty days, the College of Cardinals elected Fabio Chigi as Pope Alexander VII.