Who was the most significant Klan organizer murdered on March 31, 1868?

The most significant Klan organizer murdered on March 31, 1868, was indeed George Ashburn. He was an active figure during the Reconstruction era, notably involved in efforts to combat the Ku Klux Klan's influence and violence in the South. His assassination was emblematic of the intense conflict during this period, marked by violent resistance to the changes being implemented by the Reconstruction government, especially those aimed at ensuring civil rights for freedmen and maintaining a Republican presence in Southern politics.

The other individuals listed did play notable roles in history, but they were not murder victims associated with the Klan in the same manner as Ashburn. Amos T. Akerman served as the U.S. Attorney General and was instrumental in prosecuting Klan members, while Rufus Bullock was the governor of Georgia who faced significant Klan opposition, and Jefferson Davis, the president of the Confederacy, was not directly involved with the Klan's activities during that period. Ashburn's assassination highlights the dangers faced by those opposing the Klan and illustrates the tumultuous political landscape of post-Civil War America.