Final answer:
W. E. B. Du Bois helped to found the National Association for the Advancement of Colored People (NAACP) in 1909, which became the leading civil rights organization challenging segregation and advocating for African American equality. Du Bois was initially offered a nominal role but soon became highly influential through his work on the publication The Crisis.
Step-by-step explanation:
The prominent civil rights organization that W. E. B. Du Bois helped to found in 1909 is the National Association for the Advancement of Colored People (NAACP). Following disagreements with other African American leaders such as Booker T. Washington, who advocated for a more conciliatory approach to racial issues, Du Bois championed a more confrontational strategy to secure equal rights and oppose discriminatory laws. His efforts, along with those of other activists, led to the creation of the NAACP in response to the pervasive injustices following the end of Reconstruction.
The NAACP quickly rose to prominence as the leading civil rights organization, engaging in legal challenges against segregation and fighting for African American equality. It initially had a significant number of white liberals among its national officers, but later it saw greater leadership from African Americans. Du Bois, despite being given a 'token' position initially, became one of the most influential members of the NAACP, utilizing his role to further civil rights discourse and action through the publication The Crisis.
Moreover, by establishing The Niagara Movement in 1905, Du Bois set the foundation for what would become the NAACP, a continued force in the fight for civil rights and an organization that remains active in advocating for social justice to this day.