The Union and the Confederacy faced very different tasks in the war. The South had to defend its territory and force the federal government to halt military action. The North had to bring the Confederacy to its knees by invading the South and isolating it from potential allies abroad. While most northern leaders believed that the nation could be reunited without challenging the institution of slavery, enslaved Southerners immediately looked for ways to loosen their bonds. Meanwhile northern abolitionists worked to convince Lincoln and Congress that only emancipation could resolve the problems that had led to war.