Rapes happened often, which is a typical Scorpionic/Plutonian exhibition of power through sex and violence.

According to an article in the New York Times about two of the most notorious slave traders in the business:

"Isaac Franklin and John Armfield, were daring “pirates” or “one-eyed men,” a euphemism for their penises. The women they bought and sold were “fancy maids,” a term signifying youth, beauty and potential for sexual exploitation — by buyers or the traders themselves. 'To my certain knowledge she has been used & that smartly by a one eyed man about my size and age, excuse my foolishness,' Isaac Franklin’s nephew James — an employee and his uncle’s protege — wrote in typical business correspondence, referring to Caroline Brown, an enslaved woman who suffered repeated rape and abuse at James’s hands for five months. She was 18 at the time and just over five feet tall.  Franklin and Armfield, who headquartered their slave trading business in a townhouse that still stands in Alexandria, Va., sold more enslaved people, separated more families and made more money from the trade than almost anyone else in America. Between the 1820s and 1830s, the two men reigned as the “undisputed tycoons” of the domestic slave trade...few profited more than the two slave traders."

Scorpionic/Plutonic power is a fixed and all-consuming power, and as such, when this energy feels threatened, they strike and they strike as ruthlessly and viciously as possible. Those that had a strong sense of dignity and pride and showed any sort of resistance (often fighting back or choosing death over such a demeaning existence), were often killed. This is also why Haiti is seen as a third-world country to this day, because this country had the courage to rise up and resist French rule, mostly through the heroic efforts of the brilliant French general Toussaint L'Ouverture (who, incidentally had Scorpio and Pluto dominance as well as a Scorpio midheaven; His MC is actually conjunct his Pluto in Scorpio in the 10th house, which meant that being a leader of a violent, ruthless, unprecedented, and complete revolution to liberate himself as well as his people was his life's work and lasting legacy. This is an excellent example of what Scorpio/Pluto energy is capable of when positively oriented, but I digress). Scorpio/Pluto energy is as weak as it is strong, and it has no use for what it cannot control, conquer, and bend to its will. If a power exchange couldn't be done through death, it could be done through sex, with a lot of white men either raping their slaves, or through European traders marrying their African allies' women, which was a practice called cassare. A lot of coastal African ethnic groups used these marriage alliances as a means to gain political and financial advantages, and it was very common in the early days of the slave trade. This method of obtaining political and economic bonds through sex is an infinitely Scorpio/Pluto/Lilith concept.

I mentioned that the slave trade started in the Pluto in Leo generation, which is highlighted by the clash between authoritarianism and individualism. This generation was egotistical, and had the will to win against all odds, hence the rise of colonization (as well as imperialism) and the evils that it produced. As members of this generation, these people (mainly men) wanted power over their own lives and were prepared to challenge established structures. They also gave way to their sexual appetites, which often got out of hand, becoming overwhelming, hence the excesses.  Pluto takes about 248 years to make a full transit of the astrological signs. Its time to pass through the signs can vary from between 12 and  32 years, as it has an unusual orbit.  For 400 years, slavery was the accepted law of the land.  This would mean that Pluto went through a full transit of all the zodiacal signs twice during the slavery era. Pluto is considered a transpersonal planet; as such, its manifestations were reflected in these cycles.

Starting with the extreme action and ruthlessness of slavery in general (Aries), the extreme greed and gluttony of the white ruling class that got the best of everything while giving slaves literal scraps to eat (Taurus), the introduction of a new idea of seeing these slaves as less than human, as a justification of such a barbaric practice (Gemini), the destruction of families through slave masters selling off various family members to other plantations (Cancer), the intense and willful expression of power and pride that left the slaves (Leo), the emphasis on purity and perfection in the white race with the introduction of the "one drop rule" (Virgo), the introduction of a concept called equality is first taking hold in the minds of people through the abolitionist movement (Libra), the subjugation of a race of people through sex, violence, and death (Scorpio),  the complete erasure of the mores, religions and values of these African transplants and the forced introduction of Christianity and obedience in its stead (Sagittarius), the irony of the reality of slavery as a backdrop to the whites rebelling against the old power structure represented by the British empire (Capricorn), the establishment of a new country and which was built by slaves (Aquarius) and and lastly, the delusion of the institution of slavery shattered the abolitionist forces take effect; disillusionment and confusion takes hold on both races: the whites turn bitter and racist in the wake of the destruction of their way of life and the blacks are left to figure out how to survive in this strange new wold of freedom. (Pisces).