slaves and free blacks also fought with the rebels during the revolutionary war. washington allowed slaves to be freed who fought with the american continental army. rhode island started enlisting slaves in 1778. rhode island promised money to owners whose slaves enlisted and lived to gain freedom. during the course of the war, about one fifth of the northern army was black. in 1781, baron closen, a german officer in the french royal deux-ponts regiment at the battle of yorktown, estimated the american army to be about one-quarter black. these men included both former slaves and free blacks.