Wang Ba was from Yingyang during the late Western Han Dynasty. When Liu Xiu raised his army and passed through Yingyang, Wang Ba and a group of friends joined him. After enlisting, Wang Ba proved to be extremely loyal, winning many battles. He rendered great service in the decisive battle against Wang Mang's forces at Kunyang, earning Liu Xiu's deep trust.

Later, when Liu Xiu's troops crossed the Yellow River to confront Wang Lang in Handan, Hebei, their military campaign suffered significant setbacks. Wang Lang offered a hefty reward for Liu Xiu's capture, making the situation extremely perilous. At this critical juncture, Wang Ba's friends quietly slipped away, leaving only Wang Ba behind.

Liu Xiu remarked to Wang Ba, "All those who joined me in Yingyang have now departed, only you remain. Truly, 'strong winds know sturdy grass'!"

After Liu Xiu eventually unified the empire, he appointed Wang Ba as a general and always held him in high regard.