What was Lincoln's first priority during the civil war?

While Lincoln is known for ending slavery, he felt that it had to be eliminated in an orderly (not an abrupt) manner. When he became president, his first priority, in keeping with his oath of office, was to preserve the Union and defend the Constitution. But almost immediately, southern states were beginning to secede from the Union, as a result of the slavery issue. Lincoln had previously been willing to allow states that already had slavery to maintain it, but when secession began, he saw the urgency of bringing slavery to an end, so that the union could be preserved. And it was then that he began writing what became the Emancipation Proclamation.