On April 12, 1633, chief inquisitor Father Vincenzo Maculani da Firenzuola, appointed by Pope Urban VIII, begins the inquisition of physicist and astronomer Galileo Galilei. Galileo was ordered to turn himself in to the Holy Office to begin trial for holding the belief that the Earth revolves around the sun, which was deemed heretical by the Catholic Church. Standard practice demanded that the accused be imprisoned and secluded during the trial.

Four of the bloodiest years in American history begin when Confederate shore batteries under General Pierre G.T. Beauregard open fire on Union-held Fort Sumter in South Carolina’s Charleston Harbor on April 12, 1861. During the next 34 hours, 50 Confederate guns and mortars launched more than 4,000 rounds at the poorly supplied fort. On April 13, U.S. Major Robert Anderson surrendered the fort. Two days later, U.S. President Abraham Lincoln issued a proclamation calling for 75,000 volunteer soldiers to quell the Southern “insurrection.”

After three days of fierce combat and over 10,000 casualties suffered, the Canadian Corps seizes the previously German-held Vimy Ridge in northern France on April 12, 1917.

On April 12, 1945, President Franklin Delano Roosevelt passes away partway through his fourth term in office, leaving Vice President Harry S. Truman in charge of a country still fighting the Second World War and in possession of a weapon of unprecedented and terrifying power.

On April 12, 1961, aboard the spacecraft Vostok 1, Soviet cosmonaut Yuri Alekseyevich Gagarin becomes the first human being to travel into space. During the flight, the 27-year-old test pilot and industrial technician also became the first man to orbit the planet, a feat accomplished by his space capsule in 89 minutes. Vostok 1 orbited Earth at a maximum altitude of 187 miles and was guided entirely by an automatic control system. The only statement attributed to Gagarin during his one hour and 48 minutes in space was, “Flight is proceeding normally; I am well.”

The space shuttle Columbia is launched from Cape Canaveral, Florida, becoming the first reusable manned spacecraft to travel into space. Piloted by astronauts Robert L. Crippen and John W. Young, the Columbia undertook a 54-hour space flight of 36 orbits before successfully touching down at California’s Edwards Air Force Base on April 14.

The Soviet government officially accepts blame for the Katyn Massacre of World War II, when nearly 5,000 Polish military officers were murdered and buried in mass graves in the Katyn Forest. The admission was part of Soviet leader Mikhail Gorbachev’s promise to be more forthcoming and candid concerning Soviet history.