The significance of the Battle of Gettysburg in the American Civil War lies in its role as a turning point for the Union. Fought from July 1 to July 3, 1863, it was one of the war's bloodiest battles with nearly 50,000 casualties. The Union victory halted Confederate General Robert E. Lee's invasion of the North and strengthened Northern morale. Additionally, President Abraham Lincoln's famous Gettysburg Address, delivered later that year, underscored the importance of preserving the Union and the principles of liberty and equality, reinforcing the war's larger purpose.