How did some formerly enslaved African Americans in the South respond to advancing Union forces?

Before the Emancipation Proclamation of January 1, 1863, slaves in the South could only hope that advancing Union armies would not make themselves victims of collateral damage. After January 1, 1863, Southern slaves could look forward to being freed by advancing Union armies.The Proclamation had no effect on Union slave holding states.

With that said, many freed slaves wanted to enlist in the Union army.