Short answers, pulled from the story.
Pickett's Charge was a Confederate infantry assault on the 3rd of July 1863, ordered by General Robert E. Lee against the center of the Union line on Cemetery Ridge. It ended in a disastrous defeat, with more than half of the roughly 12,500 attacking soldiers killed, wounded, or captured, and it marked the climax of the Battle of Gettysburg.
Overall command of the assault went to Lt. Gen. James Longstreet, with three divisions led by Maj. Gen. George Pickett, Brig. Gen. J. Johnston Pettigrew, and Maj. Gen. Isaac R. Trimble. Pickett, whose name the charge carries, personally commanded only 3 of the attack's 11 brigades.
About 12,500 Confederate soldiers stepped off around 2:00 p.m. on the 3rd of July 1863. Total losses during the attack reached 6,555, including at least 1,123 killed, 4,019 wounded, and roughly 3,750 captured according to Union reports.
The name marks the farthest point Confederate troops reached inside the Union line, near the Angle, where Brig. Gen. Lewis Armistead was mortally wounded before dying two days later. The failed charge crushed Confederate hopes for a decisive Northern victory and forced Lee to retreat to Virginia.
Armistead, known for leading his brigade with his hat raised on the tip of his sword, was mortally wounded near the Angle and died two days later in a Union hospital. Per his dying wish, Longstreet delivered Armistead's Bible and personal effects to the wife of his old friend Winfield Scott Hancock, the Union general whose men had shot him.
Pickett's Charge became a central symbol of the Lost Cause, a movement that romanticized Confederate bravery and Southern leadership, especially that of Virginians like Lee and Pickett. Writer William Faulkner's famous passage on the charge helped fix this mythic image in place, which dominated popular memory of the battle by its 50th anniversary in 1913 before modern historians began revising it.