April 17

Spain and Christopher Columbus sign the Capitulations of Santa Fe, laying out the terms of his planned westward voyage in search of a new route to Asia.

Spanish monarchs Ferdinand and Isabella signed the Capitulations of Santa Fe with Christopher Columbus, granting him noble titles, a share of future profits, and governance rights over any lands he discovered in exchange for undertaking his westward voyage in search of a new trade route to Asia. The agreement financed the expedition that, months later, reached the Americas.

Martin Luther's trial before the Diet of Worms begins over his religious writings challenging the Catholic Church.

Reformer Martin Luther appeared before the Diet of Worms, an assembly of the Holy Roman Empire, to answer charges of heresy over his writings challenging Catholic Church doctrine and practices. Luther's refusal to recant, reportedly declaring "here I stand, I can do no other," became a defining moment of the Protestant Reformation, though the assembly ultimately declared him an outlaw.

Italian explorer Giovanni da Verrazzano becomes the first European to sail into New York Harbor.

Italian explorer Giovanni da Verrazzano, sailing under the French flag, became the first European recorded to enter New York Harbor, describing the area's natural beauty in his subsequent report to King Francis I. The Verrazzano-Narrows Bridge in New York was later named in his honor, though the Dutch would not establish a permanent settlement in the region for another century.

A Spanish garrison defeats a force of British-allied irregulars at Arkansas Post in one of the final clashes of the American Revolutionary War in the western theatre.

Captain Jacobo du Breuil commanded a small Spanish garrison that repelled an attack by British-backed raiders, led by trader James Colbert, seeking to capture the Spanish post on the Arkansas River. The skirmish was a minor but notable episode in the wider contest between Britain and Spain for control of the Mississippi Valley during the Revolutionary War, and helped secure Spanish control of the region.

British forces under Sir Ralph Abercromby launch a major assault on the Spanish-held city of San Juan, Puerto Rico.

The attack, mounted with a large fleet and thousands of troops, aimed to seize one of Spain's most strategically important Caribbean strongholds during the French Revolutionary Wars. Despite the scale of the assault, Spanish defenders under Ramón de Castro held the fortified city, and Abercromby's forces withdrew after roughly two weeks, marking one of Britain's rare setbacks in the Caribbean campaigns of the period.

Virginia's secession convention votes to leave the Union, becoming the eighth state to join the Confederacy.

Virginia's secession convention voted to leave the Union following President Lincoln's call for troops to suppress the rebellion after the attack on Fort Sumter, making Virginia the eighth state to join the Confederacy. The decision led directly to the western counties of the state splitting off to remain loyal to the Union, eventually forming the separate state of West Virginia.

The whaling ship Catalpa rescues six Fenian prisoners from Fremantle Prison in Western Australia, spiriting them away from British colonial custody.

The prisoners, Irish nationalists convicted for their role in Fenian uprisings against British rule, had been transported to the penal colony years earlier. A daring operation organised by Irish-American sympathisers smuggled the men aboard the American whaler, which outran pursuing British vessels to reach international waters. The escape became a celebrated episode in Irish nationalist history and embarrassed British colonial authorities.

The Treaty of Shimonoseki ends the First Sino-Japanese War, with China ceding Taiwan and other territory to Japan.

China and Japan signed the Treaty of Shimonoseki, ending the First Sino-Japanese War with a decisive Japanese victory that forced the weakened Qing dynasty to cede Taiwan, the Penghu Islands, and other territory while recognizing Korean independence. The treaty marked Japan's emergence as a major regional power and accelerated the decline of Chinese imperial influence in East Asia.

The Peak District becomes the United Kingdom's first National Park.

Designated under the newly passed National Parks and Access to the Countryside Act 1949, the Peak District's moorlands and dales in central England became a testing ground for balancing public access, conservation, and rural livelihoods. Its creation followed decades of campaigning, including the 1932 mass trespass at Kinder Scout, and paved the way for a network of national parks established across Britain over the following years.

CIA-trained Cuban exiles launch the failed Bay of Pigs Invasion in an attempt to overthrow Fidel Castro's government.

A brigade of roughly 1,400 CIA-trained Cuban exiles launched an amphibious invasion at Cuba's Bay of Pigs, intending to spark a popular uprising against Fidel Castro's government. The poorly coordinated operation collapsed within days against determined Cuban resistance, embarrassing the recently inaugurated Kennedy administration and pushing Castro further into the Soviet orbit.

Cuban exiles trained and financed by the CIA land at the Bay of Pigs in an attempt to overthrow Fidel Castro's government.

The invasion force of around 1,400 exiles aimed to spark a popular uprising against the Cuban revolutionary government but was quickly overwhelmed by Castro's forces after promised American air support was scaled back. The failed operation embarrassed the Kennedy administration, pushed Cuba further toward the Soviet Union, and contributed to the tensions that culminated in the Cuban Missile Crisis the following year.

The crippled Apollo 13 spacecraft returns safely to Earth after its harrowing journey around the Moon.

The damaged Apollo 13 spacecraft, its crew having endured a harrowing four-day ordeal after an oxygen tank explosion crippled the vessel en route to the Moon, splashed down safely in the Pacific Ocean, to the immense relief of NASA and a worldwide television audience. The mission's successful, improvised rescue became one of the space agency's most celebrated achievements.

The damaged Apollo 13 spacecraft splashes down safely in the Pacific Ocean, ending a perilous mission to the Moon.

After an oxygen tank explosion crippled the spacecraft days earlier, astronauts James Lovell, Jack Swigert, and Fred Haise had used the lunar module as a lifeboat to survive the return journey. Mission controllers on the ground improvised solutions to conserve power and remove carbon dioxide from the cabin air. The crew's safe recovery turned a near-catastrophe into one of NASA's most celebrated achievements.

Khmer Rouge forces capture Phnom Penh, ending the Cambodian Civil War and beginning a brutal genocidal regime.

Khmer Rouge forces captured the Cambodian capital of Phnom Penh, ending the country's civil war but beginning a brutal four-year totalitarian regime under Pol Pot that forcibly evacuated cities and caused the deaths of an estimated one to two million Cambodians through executions, starvation, and forced labor in what became known as the Killing Fields.

Queen Elizabeth II proclaims Canada's new constitution, completing the country's full legal independence from Britain.

Queen Elizabeth II traveled to Ottawa to formally proclaim Canada's new constitution, which included a domestic amending formula and the Canadian Charter of Rights and Freedoms, completing the process known as "patriation" that ended the need for British parliamentary approval of Canadian constitutional changes. The event marked Canada's full legal independence from the United Kingdom.

Queen Elizabeth II proclaims the Constitution Act, 1982, patriating Canada's constitution and ending the British Parliament's remaining authority to legislate for Canada.

The ceremony in Ottawa marked the culmination of decades of negotiation over how to bring Canada's founding constitutional documents fully under Canadian control. The new act added a Charter of Rights and Freedoms and an amending formula that no longer required approval from Westminster. It was the final formal step in Canada's long constitutional separation from the United Kingdom, though the monarchy remained the head of state.

An alleged 335-year state of war between the Netherlands and England's Isles of Scilly is formally declared over.

The bloodless 'war,' said to have originated from a diplomatic oversight during the English Civil War era when a Dutch fleet allegedly declared war on the Royalist stronghold of the Scilly Isles, had never resulted in any fighting and was more legend than genuine hostility. A Dutch ambassador travelled to the islands off Cornwall to sign a peace treaty, closing out what is often cited as the longest war in history — in name only.

A fertilizer plant explosion in West, Texas, kills 15 people and injures more than 160 others.

An explosion at a fertilizer storage and distribution facility in the small town of West, Texas, killed 15 people, mostly first responders, and injured more than 160 others, leveling much of the surrounding area including a nearby school and nursing home. The disaster prompted renewed scrutiny of chemical storage regulations and emergency response protocols for hazardous facilities.

The ceremonial funeral of former British Prime Minister Margaret Thatcher takes place at St Paul's Cathedral in London.

Thatcher, who led Britain from 1979 to 1990 as its first female prime minister, was honoured with a ceremonial funeral with military honours, an event normally reserved for monarchs and attended by the Queen. Thousands lined the procession route through London, while the divisive legacy of her economic and social policies drew both tributes and protests across the country on the day of the service.

The funeral of Prince Philip, Duke of Edinburgh, husband of Queen Elizabeth II, takes place at St George's Chapel, Windsor Castle.

Held amid coronavirus restrictions that limited the congregation to just 30 people, the ceremony combined military tradition with personal touches reflecting Philip's decades of naval and public service. He had died on April 9 at age 99, having been the longest-serving consort in British history. The pared-down, socially distanced service was widely noted for the image of the Queen mourning alone in a pew.