I think you should put paratheses around it.
Although not recognized immediately after the battle and after the war. It's significance became noted after Lincoln's assignation in 1865. Politicians and historians began to analyze the significance of the speech after his death to further understand the war and the abolishment of slavery.
Answer: The correct answer is : It has a disadvantage since Duke promotes the conspiracy theory of the genocide of white people and ensures that the Jews are organizing the white genocide. Duke supports voluntary racial segregation, white separatism, anti-communism, the preservation of Western culture, is a holocaust denier.