Final answer:
W. E. B. Du Bois identified prejudice against Blacks due to skin color as their greatest post-Civil War obstacle, emphasizing this through the concept of double consciousness in 'The Souls of Black Folk' and championing civil rights activism.
Step-by-step explanation:
W. E. B. Du Bois, in The Souls of Black Folk, identifies the greatest obstacle facing Blacks after the Civil War as the prejudice rooted in the color of their skin. This racism created a pervasive environment of disenfranchisement for African Americans, capturing the struggle for civil rights and the quest to be recognized and respected as equals.
Du Bois's central concept of double consciousness highlights the difficulties faced by Black Americans as they were forced to see themselves through the bias and contempt of a society that judged them based on race. Du Bois advocated for a steadfast refusal to accept segregation and argued for the importance of protest and agitation for voting rights and civil liberties, challenging the more accommodating stance of his contemporary, Booker T. Washington. His co-founding of the NAACP and his sociological work underscored a lifelong dedication to the fight against racial injustices.