30. April

The congregation had just left the Ascension Day procession when the crossing tower came down. No one was killed. The chapter repaired the vaults but never raised another tower, and the nave was never built.

Every elector voted for him: 69 of 69. He never joined a party, the only president not to. John Adams, the runner-up, became the first vice president.

On the balcony of Federal Hall on Wall Street, New York, then the capital. Robert Livingston, Chancellor of New York, gave the oath; Washington then read the first inaugural address to Congress in the Senate chamber inside.

On the balcony of Federal Hall in New York, the first capital. He was the only president elected unanimously by the Electoral College.

Joseph Hooker had twice Lee’s numbers and a good plan; Lee split his smaller army twice and beat him. Lee’s greatest victory cost about 24,000 casualties (NPS).

Gunboats that had run past Vicksburg’s batteries ferried Grant’s troops across the Mississippi, unopposed. “But I was on dry ground on the same side of the river with the enemy,” Grant wrote.

The poet and inventor Charles Cros deposited a sealed letter at the Académie des sciences describing how to trace sound on a disc, etch the trace into a groove and play it back with a stylus: the principle of the phonograph. He could not afford to build one. The envelope was opened on 3 December…

In a Friday Evening Discourse at the Royal Institution, J. J. Thomson argued that cathode rays are particles far smaller than any atom. His October paper measured their mass-to-charge ratio at about a thousandth of a hydrogen ion’s. He called them corpuscles; the world took up the electron, the…

“A New Determination of Molecular Dimensions” worked out the size of sugar molecules, and Avogadro’s number, from how sugar diffuses through water and makes it thicker. It is dedicated to Marcel Grossmann. Its method turned out to be useful for anything from cement mixes to milk, and Pais found it…

A village near Wardha in central India, chosen because it was poor and had no road. His mud-walled hut, Bapu Kuti, became the working headquarters of the national movement.

The 1935 constitution set a condition: the vote was theirs if 300,000 women said yes in a plebiscite within two years. 447,725 did.

With Soviet troops a few hundred metres away, Hitler shot himself; Eva Braun, whom he had married the day before, took poison. In his will he named Admiral Dönitz his successor.

Hanoi set up Group 559, named for the month it was founded, to move men and supplies south through the mountains of Laos and Cambodia. Porters on foot became trucks, roads and in the end a fuel pipeline: the Vietnamese call it the Trường Sơn road, after the range it followed. No amount of bombing…

While the last American helicopters lifted off the embassy roof, North Vietnamese tanks rolled through the gates of the Independence Palace. Vietnam was reunified under communist rule the next year.

Hanoi’s General Offensive and Uprising of spring 1975, under General Văn Tiến Dũng. It began in the Central Highlands with roads cut and feints at Pleiku and Kontum, and ended eight weeks later in Saigon. The last stage was named the Ho Chi Minh Campaign.

The United States backed South Vietnam against the communist North and the Viet Cong, from advisers in the 1950s to more than half a million troops in 1968. The band starts on the date the U.S. Department of Defense uses. The catalogue’s own Vietnam War timeline tells it in full. A 1995…

Two days into his presidency, Minh told his forces on the radio to stop fighting and stay where they were, and waited at the palace to hand over power.

Tank 843 rammed a side gate and stuck; tank 390 broke through the main gate. At about 11:30 Bùi Quang Thận, commander of tank 843, raised the Front’s flag on the roof. Minh and his cabinet were waiting inside to be taken. Both tanks are now national treasures, in two museums in Hanoi; the city was…

CERN put the web's software in the public domain, free for anyone to use and build on without royalties. Gopher, its main rival, had just started charging licence fees; the web took over.

About 25,000 people walked a corridor across East Texas and western Louisiana and found 84,000 pieces, some 38 percent of the orbiter by weight. Two searchers, Jules “Buzz” Mier and Charles Krenek, died when their helicopter crashed. Nobody on the ground was hurt by the debris.

The first spacecraft to orbit Mercury, from March 2011. It confirmed water ice in craters near the poles that never see sunlight, then ran out of fuel and crashed into the planet.