April 28

Roman Emperor Constantius II enters Rome for the first time, celebrating his victory over the usurper Magnentius.

Roman Emperor Constantius II entered Rome for the first time during his reign, staging an elaborate ceremonial procession to celebrate his recent victory over the usurper Magnentius, a display intended to reinforce his legitimacy despite having spent little time in the city that remained Rome's symbolic, if no longer primary political, capital.

Conrad of Montferrat, the newly elected King of Jerusalem, is assassinated by the Hashshashin in Tyre.

Conrad of Montferrat, who had just been elected King of Jerusalem after skillfully defending the Crusader states, was assassinated in the streets of Tyre by members of the Hashshashin, a secretive sect, in a killing whose exact motive and sponsor remain debated by historians to this day.

Spanish forces win the Battle of Cerignola, considered one of the first European battles decided by gunpowder small-arms fire.

Spanish forces under Gonzalo Fernández de Córdoba decisively defeated a French army at the Battle of Cerignola in southern Italy using coordinated infantry firearms and field fortifications, a victory widely regarded by military historians as one of the first major European battles decided primarily by gunpowder small-arms fire rather than traditional cavalry and pike formations.

Maryland becomes the seventh state to ratify the U.S. Constitution.

Maryland became the seventh state to ratify the newly drafted United States Constitution, helping build the momentum needed to reach the nine-state threshold required for the document to take effect and replace the weaker Articles of Confederation as the nation's founding governing framework.

Crew members aboard HMS Bounty mutiny against Captain William Bligh, setting him and loyal crew adrift in the Pacific.

Sailors aboard the British Royal Navy vessel HMS Bounty, angered by their captain's harsh discipline, mutinied and set Captain William Bligh and 18 loyal crew members adrift in a small open boat in the Pacific Ocean. Bligh's subsequent 47-day, 3,600-mile voyage to safety became a celebrated feat of navigation and survival.

Chinese and Irish immigrant laborers lay ten miles of track in a single day on the First Transcontinental Railroad, a feat that still stands as a record.

Chinese and Irish immigrant laborers working for competing railroad companies laid an extraordinary ten miles of track in a single day near Promontory, Utah, in a demonstration of speed and efficiency during the final push to complete the First Transcontinental Railroad, a record for single-day track-laying that has never been broken.

Wembley Stadium opens in London, initially known as the Empire Stadium.

Wembley Stadium, initially built as the Empire Stadium for the British Empire Exhibition, opened in London and hosted its first FA Cup Final, quickly becoming one of the most iconic sporting venues in the world and the traditional home of English football for over eight decades before its later reconstruction.

Benito Mussolini is executed by Italian partisans a day after his capture.

Italian partisans executed former dictator Benito Mussolini and his mistress, Clara Petacci, by firing squad a day after their capture, and their bodies were later publicly displayed hanging upside down in a Milan square, a grim symbolic end to over two decades of Fascist rule in Italy.

Muhammad Ali refuses induction into the U.S. Army on religious grounds, resulting in the loss of his boxing title and license.

Heavyweight boxing champion Muhammad Ali refused induction into the U.S. Army on religious and moral grounds, citing his Muslim faith and opposition to the Vietnam War, a stand that cost him his boxing title, license, and passport for over three years but later cemented his legacy as a symbol of principled conscientious objection.

Elevated radiation levels detected in Sweden lead Soviet authorities to publicly acknowledge the Chernobyl nuclear disaster for the first time.

Radiation detection equipment at a Swedish nuclear power plant, located hundreds of miles from Chernobyl, registered abnormally high levels of airborne radioactivity, prompting Swedish officials to press Soviet authorities for an explanation and forcing the Soviet Union to publicly acknowledge the Chernobyl disaster for the first time, two days after it occurred.