Final answer:
Abraham Lincoln issued the Emancipation Proclamation due to military necessity and diplomacy.
Step-by-step explanation:
Another cause for Abraham Lincoln issuing the Emancipation Proclamation was military necessity and diplomacy. The proclamation aimed to undermine the South's ability to fight in the Civil War by freeing the slaves who were working in the fields, which freed up southerners to fight against the Union. Additionally, embracing emancipation in the Union cause would create problems for British recognition of the Confederacy because of the anti-slavery sentiment in Britain. Lincoln hoped that proclaiming emancipation would reenergize citizens who might support emancipation and black enlistment to help bring Union victory.