Abraham Lincoln's Emancipation Proclamation formally took effect, declaring enslaved people in Confederate territory free and reframing the Civil War as a fight against slavery.

The Metropolitan Railway opened in London, launching the world's first underground passenger railway and transforming urban transit forever.

Union General Ambrose Burnside's attempt to flank Lee's army collapsed into chaos as torrential rain turned Virginia roads into impassable mud.

Abraham Lincoln delivers a 272-word address at the dedication of a Civil War cemetery, redefining the war as a test of democracy itself.

Union forces under General Ulysses S. Grant launched the Battle of Chattanooga with an assault on Orchard Knob, beginning three days that broke the Confederate siege.

Union troops under Ulysses S. Grant stormed Missionary Ridge outside Chattanooga, breaking Confederate lines and securing Tennessee for the North.