Both races should rejoice in gratitude,

...I wish to say one thing of importance to both (white and colored people) in order that the white race may be just and kind to the colored and that the colored race may in turn be grateful and appreciative toward the white.
The great proclamation of liberty and emancipation from slavery was made upon this continent. A long bloody war was fought by white men for the sake of colored people. These white men forfeited their possessions and sacrificed their lives by thousands  in order that colored men might be freed from bondage. The colored population of the United States of America are possibly not fully informed of the wide-reaching effect of this freedom and emancipation upon their colored brethren in Asia and Africa where even more terrible conditions of slavery existed. Influenced and impelled by the example of the United States, the European powers proclaimed universal liberty to the colored race and slavery ceased to exist....
Both races should rejoice in gratitude, for the institution of liberty and equality here became the cause of liberating your fellow-beings elsewhere.

‘Abdu’l-Bahá: Bahá’í World Faith P.269