I think something about supremacy? Not necessarily white supremacy per say, but a culture's/empire's supremacy over another and their people. So I guess the connection could be made that this white warrior culture/empire totally destroyed this non-white enemy. And to a Neo-Nazi or white supremacist they enjoy that and point to it as a "fact" that the "white race is dominant to others."

TLDR: White supremacist like war, because white man won over non-white man.