Here's another account of the same incident-

"G. W. A. writes to the Columbus Sun that General Forrest called up twenty-six of his negroes, the other night, and gave them their choice to go at once to the Yankees,
or join the army and fight by his side, and have their freedom at the end of the war. Twenty-five who said they were willing to take up arms, stepped out.
One said he did not want a gun, but he 'would drive a wagon to h--l for Massa Bedford, if he would tell him to.' "
(my emphasis)

The Tri-Weekly Herald, Newberry, SC, April 6, 1865
http://chroniclingamerica.loc.gov/lccn/sn86053216/1865-04-06/ed-1/seq-1/#date1=04%2F06%2F1865&index=0&date2=4%2F6%2F1865&searchType=advanced&language=&sequence=0&lccn=sn86053216&words=Forrest&proxdistance=5&rows=20&ortext=&proxtext=
&phrasetext=&andtext=forrest&dateFilterType=range&page=1

CW newspaper items are not always reliable but it's probably more reliable than this-
https://cwcrossroads.wordpress.com/2015/01/27/historians-freak-out-about-freaking-out-really/#comment-44508