After finding out that Frodo's Ring was actually the One Ring, Gandalf persuaded Frodo to leave the Shire discreetly. Frodo sold Bag End and bought a house in Buckland to make people think that he had merely returned back to the place he had grown up.

Fredegar (Fatty) Bolger, a friend of Frodo's, and Meriadoc Brandybuck, reached Crickhollow earlier to prepare the house for Frodo.

The morning after arriving at Crickhollow, the four hobbits (Frodo Baggins, Samwise Gamgee, Meriadoc Brandybuck and Peregrin Took), set out on their journey to bring the ring out of the Shire. Fatty Bolger's task was to stay behind at Crickhollow and make it believed, for as long as possible, that Frodo Baggins was still living in the Shire. In this way he could also inform Gandalf about the other hobbits' whereabouts should Gandalf suddenly turn up.

A few days later, Black Riders crept into the garden of Crickhollow in search of Frodo. Upon seeing them, Fatty Bolger fled to the nearest home in search of help. The Brandybucks blew the Horn-call of Buckland, which had not been sounded for a hundred years. Answering calls were heard.

By then the Black Riders knew that Frodo was no longer in the Shire, and the rode off.

While the War of the Ring progressed, Fatty was taken prisoner in the Shire by Sharkey's men. He was leader of a band of rebels that had their base in the Brockenbores by the hills of Scary. When Frodo released the prisoners, Fatty was one of the first out, but his time in prison meant he was 'Fatty' no longer.