Final answer:
Gettysburg was the site of a crucial Civil War battle in Pennsylvania where Lee's Confederate forces were defeated, marking a turning point in the war.
Step-by-step explanation:
Lee invaded Pennsylvania in the summer of 1863, marking a significant turn in the Civil War with the Battle of Gettysburg.
The battle was a pivotal moment, as Confederate forces led by General Robert E. Lee clashed with the Union Army from July 1-3, 1863, at Gettysburg, Adams County, Pennsylvania. The Union victory at Gettysburg, along with the triumph at Vicksburg, fundamentally shifted the momentum of the Civil War toward the Union.
Lee's defeat at Gettysburg, especially following the disastrous Pickett's Charge, forced the Confederacy to retreat, signaling the High Watermark of the Confederacy and the last time Lee attempted to invade the North.