24 January 1961
Elsa the lioness was one of three orphaned lions whose mother was killed in self defence by George Adamson. Adamson was a wildlife conservationist based in Kenya. He was forced to kill Elsa’s mother in self- defence when she tried to attack him. It was only after he had shot her that he realised the lion was protecting her three cubs. Adams took the cubs home and together with his wife, Joy, raised them. The two older cubs were later sent to a Rotterdam zoo, while Elsa remained with the Adamsons. Joy and Elsa developed a close bond as she slowly trained the lioness to survive in the wild. Eventually, the time came and Elsa was released into the wild. The Adamsons returned to England and upon their return a year later, found that Elsa is the mother of three cubs and that she still remembered them. Elsa died from Babesia felis, a tick-borne blood disease, on 24 January 1961. Joy documented her experience with Elsa in a book titled Born Free, published in 1996. The book was later made into a Hollywood film of the same title.
References

Father of Lions, Tribute to Elsa the Lioness, from Father of Lions, [online], Available at www.fatheroflions.org [Accessed on 15 January 2014]|PBS, Adamsons Timeline, from Public Broadcasting, [online], Available at www.pbs.org [Accessed: 15 January 2014]