Bilbo Baggins celebrates the famous birthday party at the beginning of The Fellowship of the Ring.
In the novel’s opening chapter, Bilbo holds a lavish party for his 111th birthday in Hobbiton. His cousin and adopted heir, Frodo Baggins, also celebrates his 33rd birthday on the same day. Bilbo uses the occasion to make a dramatic farewell speech before disappearing with the help of the One Ring.
The party is important because it connects The Lord of the Rings to The Hobbit. Bilbo acquired the Ring during his earlier journey, and his decision to leave it to Frodo begins the central chain of events in the trilogy.
Readers sometimes answer Frodo because his birthday is also celebrated at the party. However, Bilbo is the host and the character whose 111th birthday gives the event its identity. Frodo’s birthday is a parallel detail rather than the main occasion.