Even though escape from bondage was a permanent feature of slave societies, at certain times the migration of runaways rose precipitously. During the colonial period, the number of fugitives remained small and those who succeeded usually posed as free people in towns and cities.  But during and after the American Revolution, the flow of runaways increased as the war disrupted the plantation system in the South and ushered in the gradual abolition of slavery in the North.  During the war, thousands fled to the British lines. For instance, in 1775, Lord Dunmore, royal governor of Virginia, offered enslaved men their freedom if they bore arms for the British. Between five hundred and six hundred men immediately responded to Dunmore's "proclamation." Too often, however, the British promise of freedom was an empty one. At the end of the war, they sent a number of Black Loyalists to the West Indies in chains. 

Slaves of the Chesapeake Bay Area and the War of 1812 from The Journal of Negro History, April 1972 by Frank A. Cassell

The disruption caused by the war between the United States and Great Britain in 1812 -1815 also sparked a migration of runaways. To break the will of the South, British commanders occupied New Orleans with black troops. Admiral Alexander Cochrane even recruited runaways to fight against the Americans in Louisiana.  In South Carolina and Georgia, black Sea Islanders left their plantations when British troops appeared. Roswell King, overseer on Pierce Butler's plantation on St. Simons Island, witnessed such an exodus among his boss' s five hundred slaves.  "I can never git over the Baseness of your ungrateful Negroes," he wrote Butler, telling him that 138 people had escaped.

Lastly, after the closing of the transatlantic slave trade in 1808 and the great expansion of the domestic slave trade from the Upper South to the lower Mississippi River Valley, the migration increasingly turned to the northern states and Canada. In the decades leading up to the Civil War, it symbolized the oppressive nature of bondage in the Southern states and revealed the inequalities faced by African Americans elsewhere in the United States.