In the mid 1830s Barnum first became famous for promoting Joice Heth, an African American woman of truly uncertain age. Heth had been exhibited by others, but Barnum brought her to New York and advertised her age as 161. As if that wasn't enough, he also claimed she was GEORGE WASHINGTON'S NURSE. He set her up in a Hotel room and charged people to see her. Heth herself, sensing a good thing, played along, singing hymns and telling stories about "dear little George."
Other people had promoted Heth before, but Barnum's approach stood out. When ticket sales began to fall off, he wrote an anonymous letter to a New York newspaper claiming that Heth was a fake--that she was actually a machine, made up of whale bone and old leather. Crowds flocked again to see if she really was a fake (or maybe, more accurately, to see if she was a real fake or a fake fake).
Heth died of natural causes in 1836. Although a prominent doctor performed an autopsy and concluded that Heth was no more than 80. Barnum countered that the doctor was a fake, he continued to claim that Heth was still alive and performing elsewhere.