Maryland's population was black and these persons were overwhelmingly enslaved. The southern plantation counties had majority-slave populations by the end of the century. In 1753 the Maryland assembly took further harsh steps to institutionalize slavery, passing a law that prohibited any slaveholder from independently manumitting his slaves. A slaveholder seeking manumission had to gain legislative approval for each act, meaning that few did so. At this stage there were few voices of dissent among whites in Maryland. Although only the wealthy could afford slaves, poor whites who did not own slaves may have aspired to own them someday. The identity of many whites in Maryland, and the South in general, was tied up in the idea of white supremacy. As the French political philosopher Montesquieu noted in 1748: "It is impossible for us to suppose these creatures [enslaved Africans] to be men; because allowing them to be men, a suspicion would follow that we ourselves are not Christians." Revolutionary War The principal cause of the American Revolution was liberty, but only on behalf of white men, and certainly not slaves, Indians or women. The British, desperately short of manpower, sought to enlist African Americans as soldiers to fight on behalf of the Crown, promising them liberty in exchange. As a result of the looming crisis in 1775 the Royal Governor of Virginia, Lord Dunmore, issued a proclamation that promised freedom to servants and slaves who were able to bear arms and join his Loyalist Ethiopian Regiment: About 800 men joined up; some helped rout the Virginia militia at the Battle of Kemp's Landing and fought in the Battle of Great Bridge on the Elizabeth River, wearing the motto "Liberty to Slaves", but this time they were defeated. The remains of their regiment were involved in the evacuation of Norfolk, after which they served in the Chesapeake area. Their camp suffered an outbreak of smallpox and other infectious diseases. This took a heavy toll, putting many of them out of action for some time. The survivors joined other British units and continued to serve throughout the war. Blacks were often the first to come forward to volunteer, and a total of 12,000 blacks served with the British from 1775 to 1783. This factor had the effect of forcing the rebels to also offer freedom to those who would serve in the Continental Army; ultimately, more than 5,000 African Americans (many of