This week's featured article at the Sobel Wiki is on France. As I've noted before, France suffers an even more unpleasant history in the Sobel Timeline than in our own, which may well reflect Sobel's annoyance at Charles de Gaulle's nationalist policies during the 1960s.
One of the minor puzzles of For Want of a Nail is trying to figure out the family relationships between the various French kings that Sobel mentions. We start off with the historical Louis XVI in the 1770s, but things become uncertain after Louis' accidental death in 1793. He is succeeded by his son Louis XVII, who is a minor at the time, and initially under a regency headed by his mother, Marie Antoinette. In our own history, all of Louis and Marie Antoinette's children were born after the October 1777 point of divergence, so the same children might not be born in the Sobel Timeline. However, all of the other royal families mentioned in Nail tracked closely with their counterparts from our world. Great Britain had a Queen Victoria and a Prince Albert in the 19th century, and Russia had a Tsar Nicholas II at the turn of the 20th century, so it seems reasonable to suppose that Louis and Marie Antoinette would have had the same four children they did in our history.
In our history, Louis's eldest son, Louis Joseph, died in infancy in June 1789 after a sudden illness, but it's anybody's guess whether the same would have happened in the Sobel Timeline. If it was Louis Joseph who succeeded to the throne, then he would have been just under twelve years old at the time of his accession. There is no further mention made of Marie Antoinette's regency after 1795, which suggests that Louis XVII reached his majority and ended his mother's regency during the course of the Trans-Oceanic War. Sobel's source for Louis XVII's reign after the end of the war is called The King on a String: The Last Years of Louis XVII, which suggests that Louis XVII did not make it very far into the 19th century.
The next French king to be mentioned is Louis XVIII, whose dislike of the British was shared by Mexican President Andrew Jackson in the 1820s. It is possible that Louis XVIII was a son of Louis XVII, but it is also possible that he was Louis Joseph's historical younger brother, Louis-Charles, born in 1785. It's even possible that he is our history's Louis XVIII, the younger brother of Louis XVI. Louis XVIII's Anglophobia suggests that he was an adult at the time of the Anglo-German occupation of Paris in the early 1800s, and thus was not the son of Louis XVII. All things considered, he was most likely the historical Louis-Charles.
The next French king is Henry V, who in 1845 was unable to provide aid to the Mexicans during the Rocky Mountain War due to France's "difficulties" with the Germanic Confederation. After him is Louis XIX, who looked upon the United States of Mexico as his protege and was willing to offer the Mexican government long-term loans in the late 1850s. Next is Louis XX, an older man who abdicated in early December 1879, and his son Louis XXI, who ruled for three weeks before being killed along with his siblings and parents by the Paris mob. Finally, there was the pretender Charles X, who sparked a civil war by landing at Calais in 1895 and claiming the French throne.
For those of you following along at home, that's six kings between 1793 and 1879, five of them named Louis. Apart from Louis XVI and his son Louis XVII, and Louis XX and his son Louis XXI, no family relationships are mentioned. Henry V may be the son of Louis XVIII; if so, he was probably born between 1810 and 1820; and based on his name, he was almost certainly a younger son who survived an older brother named Louis who died in infancy. Louis XIX is almost certainly a cousin who succeeded a childless Henry; he was probably a grandson of our history's Charles X, and would have been born around the same time as his cousin Henry, or perhaps as much as ten years earlier. Louis XX was probably the son of Louis XIX, but he might have been his younger brother. The pretender Charles X was probably a nephew of Louis XX and a first cousin of Louis XXI.