The Army consisted of numerous human followers of the Ori that were raised in their home galaxy. These devout believers were to form a crusade in order to bring Origin to the unbelievers of the Milky Way galaxy or destroy them. All the soldier's within the army firmly believed in the teachings in the Book of Origin and even though some were considered good men, they were perfectly willing to kill those they considered their enemies. (SG1: "Crusade")
The fanatical warriors of the Ori Army make use of an Ori staff weapon as their primary weapon and dress in medieval style clothing. They typically wear silver styled helmets with the mouth open and sockets for the eyes though variations do exist that cover the mouth itself. Part of their weaponry also includes swords that are held around their waists. The higher-ranking members of the army wear a wrist weapon which is capable of stunning or killing enemies. (SG1: "Crusade", "Flesh and Blood", "Line in the Sand")
While the Human commanders do lead the army, they are typically under the supervision of a Prior who retains overall command. When not in combat, the Prior often leads the army members in Prostration. The overall commander of the entire army is the Orici Adria who leads the crusade. (SG1: "Flesh and Blood", "The Quest, Part 1", "The Quest, Part 2", "Line in the Sand")
The army is only deployed in locations where there is resistance. Ori fighters are used to scout the area to determine if a Human settlement has built the Ara which symbolizes their conversion to Origin. If not, then the Ori soldiers are deployed in order to combat the unbelievers. Once victory is achieved, the enemy is rounded up with purgings done in an execution style in order to instill fear in the survivors. Some may convert but it is the prerogative of the Prior in charge on whether the settlement ultimately survives or not.
Tactics employed by the army involve the use of flanking maneuvers in order to ambush the enemy by surprise. However, typically they make use of overwhelming numbers to crush the enemy forces. Rapid deployment of troops are achieved through the use of Ori fighter's which deploy a Transportation rings platform near the target sight. Troops are then immediately ringed in from an orbiting Ori warship to the planetary theatre. (SG1: "Line in the Sand")
Parts of the army were deployed to help Adria who was accompanied by a Prior in finding out the location of Merlin's weapon. The entire group were killed to the last man after emerging from the Stargate as they were targeted by gunfire from SG-1. They were, however, able to kill the Goa'uld Ba'al. (SG1: "The Quest, Part 1", "The Quest, Part 2")
They were later sent to pacify another planet where they quickly overwhelmed the defenders who were supplied with weaponry by the Human's of Earth. However, they saw a building suddenly vanish with some of the Earth Human's inside. They were later recalled by their Prior who used his mothership to destroy the settlement. Once complete, this contigent of the army moved on to their next conquest. (SG1: "Line in the Sand")
Another element of the army was sent to the ruined world of Dakara in order to capture SG-1 who were looking for a weapon against the Ori Army. They overwhelmed their opponents, who surrendered. A Prior was present who demanded that Ori Commander Tomin slay the unbelievers. During a scuffle, the Prior was killed by a staff weapon grabbed by Lt. Colonel Cameron Mitchell thus proving to the Ori soldiers that the Prior' were not invincible; a feat achieved through a Prior disruptor. The truth was revealed to them through the Priors with the use of the Ark of Truth and it ended their crusade. (SG1: "The Ark of Truth")
- Presumably, the Ori Army returned to their home galaxy and was disbanded.