The Restless League was a group of Redguard pirates based out of a hidden cove near Stros M'Kai. The League played a critical role in the uprising there during 2E 864. Their leader was a man named Basil; other prominent members included Iszara and later her brother Cyrus. The League used the lighthouse in Saintsport as a signal for members to receive transport to their hideout.
Before Iszara joined the League sometime between 2E 862 and 2E 864, they were self-described as a "wild pack of nationalists" supporting the Crown cause. When Iszara joined, they gained the attention of Prince A'tor, the ruler of the Crowns, and worked for him in secret by removing Forebear and Imperial threats. When war came to Stros M'Kai at the Battle of Hunding Bay, the prince requested that they stay out of the conflict to keep their affiliation unknown. The last stand of the Crowns resulted in utter defeat, with A'tor's apparent death and the Imperial occupation of the island that followed. However, A'tor's wizard, Archmage Voa, managed to secure the prince's lifeforce in a soul gem and the League somehow obtained it. Feeling that the League was biding its time too long, Iszara stole the gem and planned to restore the prince but went missing.
Three months after her disappearance, Cyrus contacted the League believing Iszara was at their hideout. Basil's revelations guided him correctly to the necromancer N'Gasta, who had tricked Iszara into giving up the soul gem. With her rescued, they returned to the hideout, where Cyrus explained that N'Gasta had tricked him as well into delivering the soul gem to Richton. With this recovered and the other necessities to restore the prince in hand, Basil, Iszara and the rest of the Leaguesmen infiltrated Stros M'Kai and observed the ritual at the temple of Arkay where A'tor's body was hidden. The plan seemingly backfired, and the prince's soul was transferred to his sword. Basil nearly abandoned the mission, but Cyrus rallied them to his newfound cause: to kill Richton and drive the Imperials from Stros M'Kai.
The League played a major role in fighting the stationed troops of the Empire while Cyrus dealt with Richton in the palace. Little is known what became of the League; after the battle, Basil was referred to as Captain Basil and he was charged with the reconstruction of Stros M'Kai's old quarter. This would suggest the League's affiliation with the Crowns was made open. Because of this rebellion, Hammerfell was able to negotiate better terms for itself under the new Empire of Tiber Septim.