What did Abraham Lincoln mean by this act of justice is being done upon military necessity?

When Abraham Lincoln referred to "an act of justice being done upon military necessity," he was emphasizing the idea that certain actions, such as the Emancipation Proclamation, were justified not only as moral imperatives but also as essential for the Union's success in the Civil War. He believed that freeing enslaved people would weaken the Confederacy, undermine their labor force, and bolster the Union's military strength. This dual rationale of ethics and strategy highlighted Lincoln's belief that justice and military needs could align for the greater good of the nation.