This week's featured article on the Sobel Wiki is on Howard Washburne, the founder of "Friends of Black Mexico" and the "League for Brotherhood". In For Want of a Nail, the slaves in the Southern states were freed almost painlessly in the early 1840s, and as they left the plantations many of them emigrated across the Mississippi to the southern half of OTL's Louisiana Purchase, known in the Sobel Timeline as the Confederation of Vandalia. The presence of so many black settlers into an area that until then had been almost uniformly white created a lot of friction, and even violence. The solution was to separate Vandalia into two states along the 40th parallel (the OTL border between Kansas and Nebraska) in 1877. The newly-created state had a population of about three million, two thirds of them black. By the turn of the 20th century, most of the white inhabitants had left, and a significant minority of Southern Vandalia's population was made up of runaway slaves from the Mexican state of Jefferson, which was just across the Arkansas River.
Needless to say, this was bound to create hostility between the Southern Vandalians and the Mexicans, and that only got worse when the Mexican government put some 8,000 slaves on trial for treason after they joined an invading French army in 1914. Howard Washburne was the Governor of Southern Vandalia at the time, and in February 1915 he publicly called for an end to the treason trials and the abolition of slavery in Mexico, and formed the Friends of Black Mexico to advance those aims. On January 4, 1916, the day before the verdict was due to be handed down, 2,000 F.B.M. members stormed the prison where the slaves were being held, and freed them, at a cost of over 1100 dead and 4000 injured.
Slavery was finally abolished in Mexico on May 14, 1920, and Washburne responded by transforming the F.B.M. into the League for Brotherhood, dedicated to ending racial discrimination in Washburne's own Confederation of North America. The L.B. attracted reformers and radicals who had other agendas, and in the summer of 1922 general dissatisfaction with society in the C.N.A. led to major riots and demonstrations, which Sobel called the worst since the 1880s.
Sobel wrote For Want of a Nail in the summer of 1971, towards the end of a period that had seen the United States wracked by race riots and mass demonstrations, and the book reflects this. Sobel's C.N.A. suffered periodic bouts of widespread political violence: during a severe economic crisis in the 1880s, the country was "plagued by looters, rioters, and the like"; in 1899 a two-week spasm of political violence known as the Starkist terror resulted in 436 deaths, 13,000 injuries, and almost a billion North American pounds in property damage; and, as mentioned above, the summer of 1922 saw "major riots and demonstrations . . . the worst since the 1880's" (i.e. worse than the hundreds killed and thousands injured in 1899).
The solution to the troubles of 1922, incidentally, was offered by a Sobel Timeline analogue of Henry Ford named Owen Galloway, who was able to calm the troubled waters by subsidizing mass emigration from the C.N.A.