The Emancipation Proclamation went over like wet fart up North. It spawned Conscription Riots and the Copperheads to go Hermitile.
Why would that be embarrassing?
I think there are many embarrassing moments for the US, such as the frequent murder of US soldiers of African heritage by the insurrection, the murder of US soldiers from southern states if captured by the insurrection, and the murder of US citizens loyal to the US by the insurrection.
The correct action in that case would have been to line up twice as many southern soldiers and execute them, and to assert that any southern response to that would lead to continues similar responses. US prisoners of war should have been better treated than they were. Southern soldiers were not treated as well as they should have been, but in contrast with the southern treatment of US soldiers, southern soldiers were given liberal parole at Vickburg, Appomattox Court House and North Carolina.