George Little, "The Black Man's Burden" (1928)
Three centuries of toil and sweat for others’ gain.
Of burdens carried thru upland, desert, plain—
Cruel burdens, cutting flesh and making muscle strain.
Tomorrow, yesterday, today we toil and toil in vain,
Three centuries of cries and groans; -- monotonous refrain.
Published in Opportunity, November 1928