This article was originally posted on #FolkloreThursday.com called British Legends: Gogmagog and the Giants of Albion by zteve t evans on 25 January 2018.
According to British legend, Gogmagog was the last survivor of a mythical race of giants that ruled the island of Albion before the arrival of Brutus of Troy and his Trojan followers. Geoffrey of Monmouth, in The Historia Regum Britanniae (‘The History of the Kings of Britain’) written about 1136, tells the story of how the Trojans came into conflict with Gogmagog and the giants of Albion.
Although Geoffrey made it clear where Brutus and the Trojans originated, he revealed nothing of the history of Gogmagog and the giants of Albion. Later writers promoted several versions of a story of the origin of the giants. One tells more about Gogmagog and how he returned to haunt the descendants of the Trojans, taking over a ruined hilltop fortress in Wales now known as Dinas Brân.
This article attempts to tie the threads together to reveal more of the story of Gogmagog and the giants of Albion. It begins by briefly recalling the voyage of Brutus of Troy and the prophecy of the goddess Diana, and then the conflict between the Trojans and the giants of Albion. We then move forward in time to later centuries to the time of William the Conqueror, when a Norman knight by the name of Payn Peverel confronts the demonically possessed Gogmagog on Dinas Brân, forcing him to reveal his history and purpose and foretelling the future of Peverel and his descendants.
Brutus of Troy
According to Geoffrey of Monmouth, after the fall of Troy some of the survivors of the sack of the city, led by the Trojan hero Aeneas, fled to Italy and settled there. Their descendants began building a new civilization. One of the descendants of Aeneas in Italy was a young man who became known as Brutus of Troy. After killing his father in a hunting accident, Brutus was punished by being exiled. He left Italy and making his way to Greece, where he found many descendants of the survivors of Troy still held in slavery by a Greek king. Leading the Trojans in revolt, he won their release and led them on an epic sea voyage searching for new land to settle and rebuild their lives.
While at sea, Brutus came to an abandoned island named Leogecia and found a temple dedicated to Diana, Jupiter, and Mercury, and after performing the appropriate rites he asked the goddess for guidance. Diana appeared to him in a dream and told him of a rich and fertile island populated only by a few giants. She prophesied that he would be the first of a long line of kings that would rule the island and spread across the world. When Brutus finally arrived on the island it was called Albion, and he found it was as Diana had told him. The giants were few in number, and the tallest and most powerful was named Gogmagog.
Gogmagog and the Giants of Albion
After Brutus and the Trojans, arrived they explored the island and found it very much to their liking. Individually, the giants were much bigger and for the most part stronger than the Trojans. Only Corineus, one of the Trojan captains, could match them. However, there were only twenty-four of them and they could not match the Trojan weaponry, armour, and numbers, and the Trojans battled the giants seeking to claim Albion as their own.
One day, Brutus decided to hold a festival of thanksgiving to the gods. During the festival, with many games and events underway, Gogmagog and the giants launched an attack hoping to take the Trojans by surprise. Although the giants at first had the upper hand killing many, Brutus rallied his men and in the battle all of the giants, except their leader Gogmagog, were killed. He was spared by Brutus specifically to fight Corineus, who defeated him. With Albion now free of giants, Brutus shared out the land among his captains and followers as he saw fit. In legend, Brutus became the founder and first king of Britain and Corineus became the founder and first ruler of Cornwall.
Although Gogmagog was killed, he was to return centuries later during the Norman Conquest of Britain by King William the Conqueror. This story is told in the medieval legends or “ancestral romance” of The History of Fulk Fitz-Warine, a mixture of legend, romance, and imagination by an unknown author or compiler in about 1325-40.
Dinas Brân
According to this text, Gogmagog reappeared when William the Conqueror was travelling around Britain surveying his new domain. As he travelled in the wild hills and valleys, he came across a prominent hill that was crowned by a ruined town enclosed in wide stone walls that for a long time had lain desolate and empty. Today, the hill is called Dinas Brân and overlooks Llangollen in Wales, but the ruins that crown its top are those of a later castle and not those that intrigued William which had been built many centuries before his arrival.
As the day was drawing to a close, he decided to pitch his tents on a level plain that lay below the imposing ruins. Curious and not a little awed, he asked about the place from a local Briton and was told the following story:
Under the influence! 
British legions I believe are so true.
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