According to Mucha's son Jiří, as Sarah Bernhardt was still clinging to the pinnacle of her fame, she injured her foot on a rusty nail. For many years she tried to battle the decay of the leg, but it was no use. An amputation would necessary because it was becoming increasingly difficult to hide her infirmity.
According to Jiří Mucha's account:
"'Madame,' said Barnum on day to her, 'I will give you $50,000 for your leg if you will allow me to exhibit it in spirit.' Sarah turned the offer down, but subsequently when during her stay in New York the leg became gangrenous and surgical intervention could not be delayed any longer, she sent word to Barnum.
But the great showman was dead by then and his successors were not interested. The leg was amputated and, weighted with a heavy stone, secretly buried in the depths of the Hudson."
Image from Olga's Gallery.
From "Alphonse Maria Mucha: His Life in Art" by Jiří Mucha, p. 241.