Why did the Yongle emperor rely heavily on eunuchs?

The Yongle emperor, who was known for being domineering and highly protective of his authority, relied on eunuchs to an unprecedented degree as a means of extending his personal control beyond the traditional palace sphere.1

Because he was a military man of action who often lacked patience for standard administrative procedures and held little personal trust in the traditional scholar-official class, he utilized eunuchs for a variety of critical roles. These included serving as foreign envoys, supervising special projects such as the requisitioning of construction supplies, and acting as regional overseers of military garrisons.1

Furthermore, to safeguard his power and monitor for dissent, he established the Eastern Depot (Dongchang) in 1420, a special agency staffed by eunuchs and charged with identifying treasonable activities. By employing eunuchs in these capacities, the emperor created a system of service that was directly dependent on him, allowing him to bypass the established bureaucracy and maintain a firm grip on the governance of the Ming dynasty.1