Or, or an even more ancient bit of ancient history consider the career of Daniel. Marched 500 miles to Babylon, perhaps after being neutered. Trained in the lore of his captors. A top bureaucrat whose career spanned several empires. The leaders can play their games of musical chairs, but the bureaucracy outlives them all!
Interestingly enough, the janissaries were single, if not celebate. Imperial service is not compatible with family formation. They finally overturned their soup kettles (traditional signal for a mutiny) one time too many, and were exterminated by an even newer military unit, modeled after the European pattern.
During theor glory days, they were the most efficient and feared body of troops in the world. A big part of this was because the European troops of the day were so undisciplined and ill-regulated. While Europe became more and more effective militarily, the Ottomans stagnated and eventually became extraordinarily decadent.