Why did south change strategies in the middle of the war and decide to invade the union?

The South changed its strategy in the middle of the Civil War to invade the Union primarily to relieve pressure on Confederate resources and to gain international recognition and support, particularly from Britain and France. By taking the war into Union territory, Confederate leaders hoped to demoralize Northern civilians and force a political settlement. Additionally, successful incursions could disrupt Union supply lines and potentially sway border states to join the Confederacy. This shift culminated in notable campaigns, such as Robert E. Lee's invasion of Maryland in 1862.