What factors and events led to the union victory in the civil war?

1863-General Lee lead the Confederate troops into Pennsylvania. He surprised the units in Gettysburg and the battle was the most crucial and bloodiest of the war. The victory at Gettysburg belonged to Lincoln and the Union. Turning point; last offensive attack of the South.

i have no idea lets guess a

explanation:

it would be that mali has the worst literacy rate than the others