Kingdom of Liones

Lyonesse is a kingdom, located within Britannia, that was formerly ruled by the family of Lyonesse before a coup d'etat at the hands of the Holy Knights, which made it a puppet state. The kingdom had an alliance with the fairies before the burning of the Fairy King's Forest.

Background
The Kingdom is a large and powerful country which is protected by its knights and the Holy Knights. The Seven Deadly Sins were once an active group of knights in the kingdom before being framed for the murder of the Great Holy Knight Zaratras.It was reveal by Ban that the kingdom hold a great treasure called Horn of Cernunos which could summon a Goddess.

Plot
King Lyonesse, although realizing that a predicted Holy War would soon occur, ordered all the Holy Knights to lay down their swords in an effort to avoid war. However, the Holy Knights, believing that the war was inevitable and that protection of the kingdom was their duty, captured the king, with the current Great Holy Knights, Hendricksen and Dreyfus, assuming command. They also started enslaving and forcing the citizens to participate in military efforts while justifying their enslaving with the fact that the citizens were being forced to do something for their own protection.

The three Seven Deadly Sins - Meliodas, Ban, and Gowther - attempt to invade the Kingdom of Lyonesse in order to rescue Elizabeth who was kidnap. During their attack, an army from Camelot approaches Lyonesse with their new king, Arthur.

Trivia

 * Lyoneese, is named after a country in the Arthurian legend which is the home of Tristan.