Given the following passage  "When the Emancipation Proclamation was announced, Tennessee was mostly held by Union forces. Thus, Tennessee was not among the states enumerated in the Proclamation, and the Proclamation did not free any slaves there. Nonetheless, enslaved African Americans escaped to Union lines to gain freedom without waiting for official action. Old and young, men, women and children camped near Union troops. Thousands of former slaves ended up fighting on the Union side, nearly 200,000 in total across the South.",  answer the following question. Note that the answer is present within the text.  Question: Where did they fight?
across the South