February 24

Pope Gregory XIII issues a papal bull introducing the Gregorian calendar, correcting the drift of the older Julian calendar and establishing the calendar system used by most of the world today.

Gregory's calendar reform corrected an accumulated ten-day drift in the older Julian calendar's approximation of the solar year, adjusting the leap year rules for greater long-term accuracy. Adoption spread gradually and unevenly across countries and religious lines over the following centuries, with some nations not switching until the 20th century.

The U.S. Supreme Court establishes the principle of judicial review in Marbury v. Madison, asserting its authority to strike down unconstitutional laws.

Chief Justice John Marshall's landmark opinion in Marbury v. Madison established that the Supreme Court has the authority to strike down laws it deems unconstitutional, a power not explicitly stated in the Constitution itself but that became a foundational pillar of the American system of checks and balances.

King Louis-Philippe of France abdicates amid revolutionary unrest, leading to the establishment of the French Second Republic.

Louis-Philippe's abdication, forced by the popular uprising of the French Revolution of 1848, ended the July Monarchy and led to the establishment of the Second Republic, with Napoleon's nephew Louis-Napoleon Bonaparte elected president later that year before eventually declaring himself emperor.

Estonia declares independence, briefly, before German occupation and later Soviet annexation would repeatedly interrupt its sovereignty over the following decades.

Estonia's declaration came amid a brief window of opportunity during the chaos of World War I and the Russian Revolution, though the country was almost immediately occupied by German forces and would face repeated foreign occupations before securing lasting independence in 1991.

The German Workers' Party is reorganized and renamed the Nazi Party, unveiling its 25-point political program in Munich.

The renamed and reorganized Nazi Party unveiled its 25-point program, blending nationalist, antisemitic, and vaguely socialist economic proposals designed to appeal broadly to disaffected Germans amid the economic turmoil of the early Weimar Republic.

Egypt and Israel sign an armistice agreement, formally ending major combat operations in the 1948 Arab-Israeli War.

The armistice agreements, negotiated separately between Israel and its Arab neighbors following the 1948 war that accompanied Israel's founding, established temporary ceasefire lines rather than permanent recognized borders, leaving core territorial and political disputes unresolved for decades to come.

South Vietnamese and American forces recapture the imperial city of Hue from North Vietnamese and Viet Cong troops after weeks of fierce fighting during the Tet Offensive.

The recapture of Hue, following weeks of intense urban combat against North Vietnamese and Viet Cong forces who had seized the ancient imperial city during the Tet Offensive, came at a heavy cost and revealed the discovery of a mass grave from a massacre of civilians carried out by the occupying forces.

The Gulf War's ground campaign begins as coalition forces cross into Iraq and Kuwait, quickly overwhelming Iraqi defenses.

The Gulf War's hundred-hour ground campaign swiftly overwhelmed Iraqi defenses, which had already been severely weakened by weeks of coalition air bombardment, liberating Kuwait and pushing Iraqi forces into a chaotic retreat before a ceasefire was declared just days later.

Fidel Castro formally retires as President of Cuba after 32 years in power, handing control to his brother Raúl.

Castro's retirement, announced in a letter rather than a public address due to his declining health, ended nearly five decades of rule during which he survived numerous assassination attempts and U.S. hostility while remaining a defining, polarizing figure of the Cold War era.

Russian President Vladimir Putin orders a full-scale invasion of Ukraine, launching the largest European conflict since World War II.

Putin's invasion, launched on multiple fronts including toward the capital Kyiv, aimed for a rapid takeover but met unexpectedly fierce Ukrainian resistance. The resulting war became the largest and deadliest conflict in Europe since World War II, triggering massive Western sanctions and a global realignment of security alliances.