In January 1863, President Abraham Lincoln issued the Emancipation Proclamation, a key document during the American Civil War. This proclamation was politically motivated and symbolically significant. However, it also faced criticism from various sectors, including border states and abolitionist leaders who had differing views on its effectiveness and implications for enslaved individuals. Given this complex backdrop, which of the following statements best reflects a significant consequence of the Emancipation Proclamation on the Union war effort?