By March 1348 the Black Death, having arrived via Genoese ships the previous October, was tearing through Sicilian towns, emptying villages and overwhelming clergy who could no longer perform burial rites. The pandemic, likely caused by Yersinia pestis, would go on to kill an estimated 25 to 50 million people across Europe over the next several years, permanently reshaping economies, labor markets, and religious life.

Line 1 of the Métropolitain opened between Porte de Vincennes and Porte Maillot, giving Paris an underground rail network to rival London's. Engineer Fulgence Bienvenüe oversaw construction, while architect Hector Guimard's sinuous cast-iron station entrances became instant icons of Art Nouveau design, still recognizable as symbols of the city today.

Early tremors in March 1907 foreshadowed the full-blown Panic of 1907, a banking crisis triggered by a failed attempt to corner copper stock that spiraled into runs on trust companies. The crisis, ultimately quelled by financier J.P. Morgan personally orchestrating a bailout, exposed the fragility of a banking system with no central bank, directly spurring creation of the Federal Reserve in 1913.

With German forces advancing on Petrograd following the collapse of peace talks, Lenin ordered the Soviet government relocated to Moscow, a city that had not served as Russia's capital since Peter the Great moved it to St. Petersburg in 1712. The Kremlin, long a symbol of Tsarist power, became the seat of Bolshevik rule, a status Moscow retains to this day.

The Lend-Lease Act allowed the officially neutral United States to become what Roosevelt called the 'arsenal of democracy,' shipping tanks, aircraft, and food to nations fighting Axis powers. Over the course of the war the U.S. sent more than $50 billion in aid, decisively tipping the balance of resources toward the Allies while keeping America formally out of combat for nine more months.

Building on the success of the audio CD, Philips and Sony unveiled the CD-ROM specification, allowing compact discs to store up to 550 megabytes of computer data, an enormous leap over floppy disks of the era. The format would go on to enable everything from multimedia encyclopedias to software distribution and PC gaming through the 1990s.

Following the People Power Revolution that ended his 20-year rule, Ferdinand Marcos remained in Hawaiian exile in mid-March 1986 while newly installed President Corazon Aquino worked to consolidate control over the military and government. The peaceful uprising, driven by millions of unarmed Filipinos who blockaded tanks with rosaries and flowers, became a global template for nonviolent regime change.

The most powerful earthquake ever recorded in Japan struck 130 kilometers off the coast of Tōhoku, generating waves up to 40 meters high that obliterated coastal towns within minutes. The disaster killed roughly 19,000 people, displaced hundreds of thousands, and caused meltdowns at the Fukushima Daiichi nuclear plant, forcing the largest evacuation in Japan since World War II.