In 1908, Kaiser Wilhelm II of Germany gave an interview to the Daily Telegraph full of outbursts and outlandish statements that offended everyone in Europe. There were serious calls in Germany for him to abdicate, and while that didn't happen he did lose most of his prestige and power after the incident.
What if he actually had resigned? Would there still have been a great war, and if so what would it look like (it's true that during WWI he was mostly a figurehead but what if there had been another kaiser instead, who wasn't?)? If not, what would European diplomacy and German politics look like going forward?