During the Russo-Japanese War, Port Arthur, the Russian naval base in China, falls to Japanese naval forces under Admiral Heihachiro Togo. It was the first in a series of defeats that by June turned the tide of the imperial conflict irrevocably against Russia.

Well on its way to losing a war against Japan in the Far East, czarist Russia is wracked with internal discontent that finally explodes into violence in St. Petersburg in what will become known as the Bloody Sunday Massacre.

On January 25, 1905, during a routine inspection of the Premier Mine in Pretoria, South Africa, a mine superintendent made a glittering discovery: a 3,106-carat diamond. (Some sources say the discovery occurred on January 26.) Weighing 1.33 pounds, and christened the “Cullinan,” it was the largest diamond ever found.

On February 13, 1905, President Theodore Roosevelt delivers a speech to the New York City Republican Club.

Future president Franklin Delano Roosevelt weds his fifth cousin once removed, Eleanor Roosevelt, in New York on March 17, 1905.

On March 31, 1905, Kaiser Wilhelm of Germany arrives in Tangiers to declare his support for the sultan of Morocco, provoking the anger of France and Britain in what will become known as the First Moroccan Crisis, a foreshadowing of the greater conflict between Europe’s great nations still to come, the First World War.

Trial starts in the murder case of Thomas and Ann Farrow, shopkeepers in South London. The case would be the first resolved on the basis of fingerprint evidence.

During the Russo-Japanese War, the Russian Baltic Fleet is nearly destroyed at the Battle of Tsushima. The decisive defeat, in which only 10 of 45 Russian warships escaped to safety, convinced Russian leaders that further resistance against Japan’s imperial designs for East Asia was hopeless.

On June 19, 1905, some 450 people attend the opening day of the world’s first notable nickelodeon, located in Pittsburgh, Pennsylvania and developed by the brilliant Vaudeville impresario and showman Harry Davis. While it wasn't technically the nation's first theater for moving pictures, its runaway success made it, in many historians' view, the birthplace of the movie theater as a place for mass entertainment.

On June 30, 1905, Albert Einstein publishes “Zur Elektrodynamik bewegter Körper (On the Electrodynamics of Moving Bodies),” a paper that sets out his theory of special relativity, in the German physics journal Annalen der Physik. Einstein’s groundbreaking work shatters the foundations of physics.

Niagara Movement members begin meeting on the Canadian side of the Niagara Falls. This all-African American group of scholars, lawyers and businessmen came together for three days to create what would soon become a powerful post-slavery Black rights organization. Although it only lasted five years, the Niagara Movement was an influential precursor to the mid-20th century civil rights movement.

On October 30, George Bernard Shaw’s play Mrs. Warren’s Profession, which dealt frankly with prostitution, is performed at the Garrick Theater in New York. The play, Shaw’s second, had been banned in Britain. After only one performance, puritanical authorities in New York had the play closed. On October 31, the producer and players were arrested for obscenity, but a court case against the play failed to convict playwright, producer, or actors. Although some private productions were held, the show wasn’t legally performed in Britain until 1926.

Author O. Henry’s best-known and most beloved story, "The Gift of the Magi," is published in the December 10, 1905 issue of New York Sunday World Magazine. It tells the poignantly ironic tale of a poor but devoted couple who each sacrifice their most valuable possession to buy a gift for the other. The following April, it is published as part of his story second short story collection, The Four Million.