$150 reward [cut of runaway slave], 1838 Although it was the law of the land for more than 300 years, American slavery was challenged and resisted every day, by its victims, by its survivors, and by those who found it morally unacceptable. The long campaign to abolish the trade in human beings was one of the great moral crusades in U.S. history, and its success was the result of decades of organization and agitation by African Americans and their European American allies.