Slaves played a critical role in their own liberation. Southern slaves deserted plantations and fled to Union lines. Slaves also staged a few small insurrections during the war as the slave system itself began to unravel. Planters were stunned to see trusted house slaves and field drivers lead field hands in deserting to the Union army. Eventually, 150,000 former slaves fought as soldiers in the Union army.
The following letter suggests how the plantation system of labor and discipline was beginning to break down in the face of protracted war.
The blacks are getting worse evry day & at the end of this year I think they will be intolerable in account of bad work and the condition of the crops. I told them they must work Saturday evening but they would not do it, and a dozen of the best men, Wesley at the head, went off to Thibodeux...and last night got back with a paper from Genl. Cameron requiring them to work until the Provost Marshall had investigated the matter....I have abandoned half the cotton on this place in order to save the remainder but there is a great likelihood that the caterpillar will take what is left.... So in fact our prospect is not bright by any measure.
You will see by the inclosed slip that there is to be another call on our plantations for col[ore]d soldiers. How many will be taken can not be told at present but we shall soon know. The demand for labor will be so great [in] another year that no large plantation can be carried on at the force that will work. I shall try to lease mine out if I could. Fear do so with safety. After the war if the South gains its independence plenty of slaves can be got from Africa and to let the North take what it likes and make the most of them.
...The failure of crops under the present System need to stagger the northern sympathies and lessen the speculations to a degree which must discourage the war advocates.