Post some links then, sport.
http://www.answers.com/topic/emancipation-proclamation-and-thirteenth-amendment
And like southern whites, you often had to be truly dedicated to the cause to overcome all the barriers to even reach Union forces, whereas many southern conscripts and slaves served the Confederate needs only reluctantly.
The slaveowners were adept in getting others to do their dirty work no matter whether the exploited help was southern blacks or southern whites.