The following article contains spoilers.
Please read at your own risk.
The rebels were divided into two groups: Northern and Southern rebels. Rebel attacks on the Palace were not an uncommon occurrence, and King Clarkson blamed several of the country's problems on rebels. Both groups of rebels looked alike and all like common people, so their attacks were always unexpected and it was unknown who is attacking until the attack ends.
The Northern Rebels were formed by Spencer Illéa, the oldest son of Gregory Illéa. Northerners were known to attack much more frequently than the Southern rebels. However, they were far less likely to break in the palace and, when they did, not much damage is caused. Maxon says they lived a little north of Angeles, "in the rainy patch of Likely and Bellingham" where it is mostly ruins. Apparently, not many people are compelled settle down in that area. He also believed that they moved around a lot.
They stole books from the Palace's library and sometimes got unwed mothers out of jail. No one was exactly sure what the Northerners' true intentions were, so they were a bit of a mystery to everyone. Prince Maxon told America that his father said "...they just want to bother us, disrupt our governing...," but Maxon said he thought otherwise and believed they were searching for something. America believed that they're looking for Gregory Illéa's diaries, because she had seen them take stolen books from the Palace's library.
When their leaders, August Illéa and Georgia Whitaker, came to the palace to talk to Maxon and America, they revealed that the Northern rebels actually supported the monarchy and especially Maxon. They only wanted nominated officials and an end to the castes. They also wanted Maxon to marry America, as they admired her for every brave thing she had done and they thought she would make an excellent queen. Maxon refused to let them force him into this decision. America, although she supported their goals, was also angry that they wanted her as their pawn. However, they secretly met again with August and Georgia to ask details about the attacks of Southern rebels. August asked Maxon for weapons so that the Northern can fight the Southerners, something that Maxon had to think carefully about. America, after asking Maxon's opinion, invited the Italian princess Nicoletta and Georgia during a tea party to meet each other. Georgia explained to Nicoletta the goals of the Northern rebels and asked her to fund their weapons so they could fight the Southerners. After contemplating, Nicoletta finally accepted this request, as she wanted her country to support the future of Illéa, a possible ally. Thanks to these weapons, the Northern rebels managed to fight back the Southerners during their last attack and save many people.
Many people secretly supported them, including America's father, Kriss Ambers, and Gavril Fadaye. They all use the North Star as their symbol to recognize each other: Shalom Singer's signature, Kriss's star necklace, Gavril's lapel pin, August's compass, and a star-like tattoo that America saw on the neck of a criminal during the Convicting. They also used the number 21.
Known Northern Rebels:
- Spencer Illéa
- August Illéa
- Georgia Whitaker
- Shalom Singer
- Gavril Fadaye
- Kriss Ambers
- Jacob Digger
Possible Northern Rebels:
Unlike the Northern rebels, the Southerners' attacks were much more lethal, but only came now and then — usually about once or twice a year. Maxon told America that people always died when they came, such as when they killed Officer Tanner in the end of The Elite. They wanted to kill off the royal family, take over Illéa, and leave all of the people in the lower castes in the same place they were now, although they were making promises to change their life. In The One, when Maxon, America, Aspen, and Officer Avery were returning to the palace after visiting August and Georgia, they were attacked by a group of Southern rebels with guns. They all managed to escape, after August and Georgia ran to their rescue, but America was shot in her right arm, a non-fatal wound. During this incident, they understood that the Northerners were indeed really loyal to the crown, while the Southerners wanted them dead. In the Southerner's last attack, during Maxon's engagement ceremony, they killed many people, including the King, Queen, Celeste Newsome, other unnamed Selected girls and Anne who was America Singer's maid. They severely wounded Aspen and Maxon, who was actually protecting America. Thanks to the Northern rebels, who were secretly in the ceremony and fought them back, Maxon and many other people were saved.
In The Heir, Eadlyn mentions that her father with the help of August Illéa eradicated completely the Southern Rebels' forces.