Luckily for us Royal Flash isn't an answer to this question. However, it is George MacDonald Fraser's take on the overall German political situation of the time, and the convoluted means used to contrive the unity of hundreds of little independent duchies. It's also The Prisoner of Zenda as real politik, where there are no happy endings, and the bad guy winds up winning the day.
Flashman, escaping from a raid on a London gambling den and brothel ends up stealing Bismarck's mistress. Then, at a country house party, Flashman arranges for his rival to be beaten by a famous retired prize fighter. It's a slight that won't be forgotten, and one that several years later comes back to haunt our rogue. Tempted into Bavaria by that same woman (and a hefty pile of cash), Flashman is blackmailed, kidnapped, and forced into replacing a Danish prince. He's to marry a Duchess, on time, as the Prince is ill (with a "social disease") - and the wedding is critical for the future of Germany. Or so says Bismarck. Of course it's a trap for his old adversary, the Prince is actually a prisoner, and Flashman finds himself drawn tighter and tighter into a web of conspiracy that can only mean his death. What is a coward and a rake to do? Run away?
Don't expect great literature here, but do expect a fine turn of phrase and excellent historical research. What it all adds up to is another fun romp from MacDonald Fraser, and another fine mess for Flashman.