 Local Union commanders, who had been aggressively enforcing the Confiscation Acts to grant freedom to slaves of rebel owners, put the Proclamation into effect immediately, freeing many slaves in the area.In 1862, the Confederate Army had constructed a massive defensive earthwork at Arkansas Post, on the Mississippi River, known as Fort Hindman.It was located on a bluff 25 feet above the river on the north bank, with a mile view up and downriver.