What reasons could lincoln have for making such a move during the civil war? why didn’t lincoln free slaves in all of the united states?

Lincoln's main objective was to preserve the unity of his country, so he closely supervised the war effort, especially the selection of generals who would lead the army. In addition, the president made important decisions in the war strategy of the Union, including a naval blockade that prevented the trade of the southern states, the movements to take control of Kentucky and Tennessee and the use of gunboats to dominate the waterways. from the south. Lincoln repeatedly tried to conquer the Confederate capital at Richmond, a mission he commissioned successive generals until Grant succeeded. While the war was being waged, its complex movements to end slavery included the Proclamation of Emancipation in 1863.

1.

Such a move could disrupt the Southern economy and way of life if slaves decided not to help the Confederate war effort or decided to rebel against their masters.

The Proclamation gave the North a moral reason to continue fighting the war—the end of slavery.

2.

Border states—slave states that stayed in the Union—might strongly object to freeing all slaves during the war. Such a move might convince more people to join the Confederacy.

the answer is b your welcome : )