Final answer:
Robert E. Lee engaged Northern forces at Gettysburg in the hopes of a decisive victory and securing supplies, but the battle ended in a Union victory.
Step-by-step explanation:
Robert E. Lee engaged Northern forces at Gettysburg because he believed a decisive victory on Northern territory would force the Union to negotiate for peace and help boost Confederate morale. Additionally, Lee hoped to secure much-needed supplies for his army. However, the battle ended in a Union victory, which marked a turning point in the Civil War.
Learn more about Robert E. Lee's engagement at Gettysburg