There were and still are many guilds that opposed or threatened to attack and or destroy The State. Many of them were lead by Ex-State soldiers and/or supporters who want the thirst for power and the desire to lead a guild much like The State.
The Revolution was a Military guild much like the State that was founded by Conna Wonna, who was a First Sergeant of State Infantry III (Under the leadership of Kusan). He grouped together his friends and some lower ranking soldiers from the State Infantries. The Revolution was lead under his command as the Commander General and backed by General Helen.
Some rebel factions opposing the State, such as Disciples of Discord, Riders of Rohan, and Sparta were single-guild militaries that appeared disorganized and filled with immature people. This all changed when Gorgo left the State with Major Falcon to form Sparta. Gorgo trained the rebel factions, leading them to their first real victories. Falcon was frustrated with Gorgo, because he wanted her to work on Sparta's progression, mainly because he was too incompetent to do it himself. Gorgo was kicked by Falcon, and the rebels were then crushed like bugs.
Soren's guild, In Deorum Vivum, was also allied to the rebel factions, as he was the self-proclaimed leader of The Rebellion.