| April 6, 1896 | April 6, 1917 |
| • The Olympic games, a long lost tradition of ancient Greece, are reborn in Athens, 1,500 years after being banned by Roman Emperor Theodosius I. | • The United States formally enters the First World War. By the time the war ended on Nov. 11, 1918, more than 2 million American soldiers had served on the battlefields of Western Europe, and some 50,000 of them had lost their lives. |
| April 7, 1776 | April 7, 1966 |
| • Navy Captain John Barry, commander of the American warship Lexington, makes the first American naval capture of a British vessel when he takes command of the British warship HMS Edward off the coast of Virginia. | • The United States recovered a hydrogen bomb it had lost off the coast of Spain. |
| April 8, 563 B.C. | April 8, 1974 |
| • Gautama Buddha, the founder of Buddhism, is born in the Kingdom of Sakya along the border of present day Nepal and India. Buddha was born as Prince Siddhartha, the son of the King of the Sakya people. | • Hank Aaron of the Atlanta Braves hits his 715th career home run, a shot to left center field at Atlanta Fulton County Stadium, to eclipse Babe Ruth's record. |
| April 9, 1859 | April 9, 1959 |
| • A 23 year old Missouri youth named Samuel Clemens receives his steamboat pilot's license. He piloted his own boats until the Civil War halted steamboat traffic. He picked up the pen name "Mark Twain" from a boatman's call noting that the river was only two fathoms deep, the minimum depth for safe navigation. | • NASA introduces America's first astronauts to the press: Scott Carpenter, Gordon Cooper Jr., John Glenn Jr., Virgil "Gus" Grissom, Walter Schirra Jr., Alan Shepard Jr. and Donald Slayton. The seven men, all military test pilots, were carefully selected to take part in Project Mercury. America's first manned space program. |
| April 10, 1942 | April 10, 1951 |
| • The Baatan Death March begins in the Philippines as some 75,000 captured Filipino and American troops start a forced march to a Japanese prison camp. Hundreds of Americans and many more Filipinos would die during the six day trek, which was punctuated with atrocities committed by the Japanese guards. | • The USS Thresher, an atomic submarine, sinks in the Atlantic Ocean, killing its entire crew. One hundred and twenty nine sailors and civilians were lost when the the sub unexpectedly plunged to the sea floor 300 miles off the coast of New England. |
| April 11, 1945 | April 11, 1951 |
| • The American Third Army liberates the Buchenwald concentration camp, near Weimar, Germany. Among those saved by the Americans was Elie Wiesel, who would go on to win the Nobel Peace Prize in 1986. | • In perhaps the most famous civilian-military confrontation in U.S. history, President Harry Truman relieves General Douglas MacArthur of command of U.S. forces in Korea. The firing of MacArthur set off a brief uproar among the American public, but Truman remained committed to keeping the conflict in Korea a "limited war". |
| April 12, 1633 | April 12, 1861 |
| • The inquisition of physicist and astronomer Galileo Galilei for holding the heretical belief that the Earth revolves around the sun begins. Galileo agreed not to teach the heresy anymore and spent the rest of his life under house arrest. It took more than 300 years for the church to admit that Galileo was right and to clear his name of heresy. | • The American Civil War begins when Confederate shore batteries under Gen. P.G.T. Beauregard open fire on Union-held Fort Sumter in South Carolina's Charleston Bay. |