“Slaves who ran away in Pennsylvania to join Sir William Howe's occupation of Philadelphia or who ran away in Virginia to join Lord Dumore's "Ethiopian Regiment" found themselves dumped by their erstwhile allies in Nova Scotia or sold back into slavery in the Bahamas.”

François Bernier, quoted from Lal, K. S. (1999). Theory and practice of Muslim state in India. New Delhi: Aditya Prakashan. Chapter 4
Travels in the Mogul Empire (1656-1668)

Source: Halt's Peril

1860s, Allow the humblest man an equal chance (1860)
Context: These natural and apparently adequate means all failing, what will convince them? This, and this only; cease to call slavery wrong, and join them in calling it right. And this must be done thoroughly — done in acts as well as in words. Silence will not be tolerated — we must place ourselves avowedly with them. Douglas's new sedition law must be enacted and enforced, suppressing all declarations that Slavery is wrong, whether made in politics, in presses, in pulpits, or in private. We must arrest and return their fugitive slaves with greedy pleasure. We must pull down our Free State Constitutions. The whole atmosphere must be disinfected of all taint of opposition to Slavery, before they will cease to believe that all their troubles proceed from us. So long as we call Slavery wrong, whenever a slave runs away they will overlook the obvious fact that he ran because he was oppressed, and declare he was stolen off. Whenever a master cuts his slaves with the lash, and they cry out under it, he will overlook the obvious fact that the negroes cry out because they are hurt, and insist that they were put up to it by some rascally abolitionist.

2000s, The Real Abraham Lincoln: A Debate (2002), The Right of Secession Is Not the Right of Revolution

Source: Don Quixote de la Mancha (1605–1615), Part II (1615), Book III, Ch. 57.

As quoted in Lies My Teacher Told Me: Everything Your American History Textbook Got Wrong https://books.google.com/books?id=5m2_xeJ4VdwC&printsec=frontcover&dq=lies+my+teacher+told+me&hl=en&sa=X&ei=dV39VNWyPMmWgwTN14JQ&ved=0CCwQ6AEwAA#v=snippet&q=maltreated&f=false (2008), p. 193
2000s, 2007, Lies My Teacher Told Me: Everything Your American History Textbook Got Wrong (2007)
Context: Ideas made the opposite impact in the Confederacy. Ideological contradictions afflicted the slave system even before the war began. John Brown knew the masters secretly feared their slaves might revolt, even as they assured abolitionists that slaves really liked slavery. One reason his Harpers Ferry raid prompted such an outcry in the South was that slave owners feared their slaves might join him. Yet their condemnations of Brown and the 'Black Republicans' who financed him did not persuade Northern moderates but only pushed them toward the abolitionist camp. After all, if Brown was truly dangerous, as slave owners claimed, then slavery was truly unjust. Happy slaves would never revolt... White Southerners founded the Confederacy on the ideology of white supremacy. Confederate soldiers on their way to Antietam and Gettysburg, their two main forays into Union states, put this ideology into practice: they seized scores of free black people in Maryland and Pennsylvania and sold them south into slavery. Confederates maltreated black Union troops when they captured them.

Source: Uncommon Criminals

Source: https://founders.archives.gov/documents/Jefferson/01-24-02-0387
Source: Discussion with Jefferson (1792)

To Otto von Bismarck in June 1878, as quoted in Around the World with General Grant http://www.granthomepage.com/grantslavery.htm (1879), by John Russell Young, The American News Company, New York, vol. 7, p. 416.
1870s, Around the World with General Grant (1879)