Napoleon made himself sole ruler of France without a prior title of nobility, backed by the soldiers' loyalty to him. Who were the other first lowborn Europeans to try to convert leading their army into leading their nation?
Post-Roman Europeans, I mean, since many Roman Emperors were quite low-born before they took the purple. But after Rome, it seems like most Europeans who seized a crown were already born to high nobility. Henry IV of England was Richard II's first cousin. France's Pepin the Younger was already "Mayor of the Palace," hereditary unofficial King of the Franks, before he deposed Childeric to become king in official title as well.
But in our own time, military coups seem to have little or nothing to do with how well-born the leader is, just whether the troops will uphold him.
Who, besides Napoleon, were the first men to demonstrate this shift from the medieval "the army's behind you, and your father was elite" to the modern "the army's behind you, and never mind who your father was"?
Oliver Cromwell, I guess, but who else?
Though I cannot answer your question, I would just like to point out the fact that Napoléon was a noble. There is a common misconception that Napoléon was a lowborn but his family, the Bonaparte of Sarzana ( or Buonaparte ) are a very old Italian family who settled in Corsica sometime during the 16th century.
The nobility of the Bonaparte was recognized on September 13th 1771 by the Council of Bastia on the request of Lucien Bonaparte ( Luciano ), canon of Ajaccio and Charles ( Carlo ) the father of Napoléon. As required by the law they proved that their family has been noble for more than two century. They proved that in 1554, the Senate of Genoa made their ancestor Geronimo Buonaparte an Elder Prosecutor. The Bonaparte family is very ancient, not on the top of the nobility but very old.
Here is a transcription of the original minute that recognized the Bonaparte as nobles.