Let's go over the facts. Before his disappearance, Bob imbued his power into three animals. Cluckles, the chicken, Mooington, the cow, and Baab, the sheep. Bob stated in his letters he was going to seal away a "dark creature of the night in a land 'far' away." Note the quotes surrounding "far." Many jump to the conclusion that this actually refers to Dern Beast. But the truth is, the actual meaning is far darker. But consider this: The rooster is representative of France; the bull, of Spain; and sheep, of Greek Arcadia. Who was born in Greece? Who was educated in France? Who has relations to the royal family of Spain? That's right. Prince Philip, Duke of Edinburgh. Let's look at the aforementioned quote again. It talks of a "dark creature." Can we really take this for what it is, though? There were many obfuscated areas throughout the letters, so can we truly trust this bit to be true to the original intent of the author? I think not. Prince Philip was born the Prince of Greece and Denmark. Denmark starts with "d" and ends with "ark," just like "dark." I believe that Bob did not intend to write "dark," as in lacking light or shadowy, but rather "Denmark." As for "far," he is simply using verbal irony. England is not actually very far from Europe. So, we know that Bob is actually referring to the royal family of England. Why, though? Well, he then mentions in the same letter: "... it poses a threat to all... I am going to challenge the beast and attempt to seal it away using my..." Simply put, Bob is going to seal away the British. Many will argue that Britain is a threat to the world, so I will omit further explanation on that part; however my theory remains intact. TL;DR: Bob didn't go to Dern; rather, he is going to eliminate the British.