As we celebrate Charles Darwin’s 206th birthday this year, we also mark 150 years since the conclusion of the American Civil War. Throughout his life, Darwin remained an ardent abolitionist, dating from his travels to South America, where he witnessed the buying and sales of African slaves. Although his name is invoked in the phrase “social darwinism,” Darwin himself never endorsed laissez-faire economics, war or racism and often expressed a deep-felt opposition to slavery, as observed in these letters.
In a letter to his sister Catherine Darwin, 22 May [– 14 July] 1833, from his travels in Brazil:
I have watched how steadily the general feeling, as shown at elections, has been rising against Slavery.— What a proud thing for England, if she is the first Europæan nation which utterly abolishes it.— I was told before leaving England, that after living in Slave countries: all my opinions would be altered; the only alteration I am aware of is forming a much higher estimate of the Negros character. — it is impossible to see a negro & not feel kindly towards him; such cheerful, open honest expressions & such fine muscular bodies; I never saw any of the diminutive Portuguese with their murderous countenances, without almost wishing for Brazil to follow the example of Hayti.
To John Maurice Herbert (a friend from Cambridge), 2 June 1833
It does ones heart good to hear how things are going on in England.— Hurrah for the honest Whigs.— I trust they will soon attack that monstrous stain on our boasted liberty, Colonial Slavery.— I have seen enough of Slavery & the dispositions of the negros, to be thoroughly disgusted with the lies & nonsense one hears on the subject in England.
To Charles Lyell (foremost geologist in Darwin’s day), 25 Aug 
But I will not write on this subject (ie slavery); I shd perhaps annoy you & most certainly myself.— I have exhaled myself with a paragraph or two in my Journal on the sin of Brazilian slavery: you perhaps will think that it is in answer to you; but such is not the case, I have remarked on nothing, which I did not hear on the coast of S. America. My few sentences, however, are merely an explosion of feeling.
How could you relate so placidly that atrocious sentiment about separating children from their parents; & in the next page, speak of being distressed at the Whites not having prospered; I assure you the contrast made me exclaim out.—But I have broken my intention, & so no more on this odious deadly subject.—
To Asa Gray (a botanist at Harvard University with whom Darwin collaborated), 16 Oct 
Our verdict was, that the N. was fully justified in going to war with the S.; … after your victories in Kentucky & Tennessee, [you ought] to have made peace & agreed to a divorce. How curious it is that you all seem to believe that you can annex the South; … I would then run the risk of your seizing on Canada (I wish with all my heart it was an independent country) & declaring war against us. But slavery seems to me to grow a more hopeless curse. … This war of yours, however it may end, is a fearful evil to the whole world; & its evil effect will, I must think, be felt for years.— I can see already it has produced wide spread feeling in favour of aristocracy & Monarchism: no one in England will speak for years in favour of the people governing themselves.
To J. D. Hooker (a botanist, Director of Royal Botanical Gardens, and Darwin’s closest friend), 24 Dec 
Slavery draws me one day one way & another day another way. But certainly the Yankees are utterly detestable towards us.— What a new idea of Struggle for existence being necessary to try & purge a government! I daresay it is very true.
To Asa Gray, 19 Jan 
Well, your President has issued his fiat against Slavery—God grant it may have some effect.— I fear it is true that very many English do not now really care about Slavery; I heard some old sensible people saying here the same thing; & they accounted for it (& such a contrast it is to what I remember in my Boy-hood) by the present generation never having seen or heard much about Slavery.—
To Asa Gray, 23 Feb 
I do, most truly think it dreadful that the South, with its accursed Slavery, shd triumph, & spread the evil. I think if I had power, which thank God I have not, I would let you conquer the border states, & all west of Mississippi & then force you to acknowledge the Cotton States. For Do you not now begin to doubt whether you can conquer & hold them? I have inflicted a long tirade on you.—
To Asa Gray, 19 Apr 
Well I suppose we shall all be proved utterly wrong who thought that you could not entirely subdue the South. One thing I have always thought that the destruction of Slavery would be well worth a dozen years war.
To Asa Gray, 15 Aug 
We continue to be deeply interested on American affairs; indeed I care for nothing else in the Times. How egregiously wrong we English were in thinking that you could not hold the South after conquering it. How well I remember thinking that Slavery would flourish for centuries in your Southern States!
To Asa Gray, 16 Apr 
I declare I can hardly yet realise the grand, magnificent fact that Slavery is at end in your country. Farewell my good & kind friend—
Yours most sincerely,