OTD:

In 301 CE, the microstate of San Marino was founded, traditionally regarded as the world's oldest republic, established by Saint Marinus on Mount Titano.

In 1189, Richard I, known as Richard the Lionheart, was crowned King of England, noted for his leadership in the Third Crusade and his chivalrous reputation.

In 1783, the Treaty of Paris was signed in France, officially ending the American Revolutionary War and recognizing the United States' independence.

In 1939, France and the United Kingdom declared war on Germany, marking the beginning of World War II in Europe after Germany's invasion of Poland.

In 1950, during the Korean War, the Battle of Pusan Perimeter reached a critical point as UN forces halted the North Korean advance, marking a turning point in the conflict.

In 1967, Sweden switched from driving on the left to the right side of the road in a well-coordinated event known as "Dagen H" to improve road safety.

In 1969, the first ATM in the United States was installed in Mountain View, California, revolutionizing banking by providing 24-hour access to cash.

In 1977, the U.S. Open became the first Grand Slam tennis tournament to offer equal prize money to male and female champions, advancing gender equality in sports.

In 2002, the Basel II Accord was finalized in Switzerland, introducing new international banking regulations focused on risk management and financial stability.

In 2015, the AI system AlphaGo defeated European Go champion Fan Hui, marking the first time an AI had beaten a professional human player in Go.