War against the Elder One

The war against Corypheus was a war between the reestablished Inquisition and Corypheus, a powerful darkspawn and former Tevinter magister. It coalesced in 9:41 Dragon amidst the chaos of the Mage-Templar War as Corypheus manipulated the Mage Rebellion, the Templar Order, and Grey Wardens of Orlais to serve his purposes, threatening the whole of Thedas.

Background
At some point between 9:31 and 9:37 Dragon, the darkspawn and former magister Corypheus awoke in a Grey Warden prison in the Vimmark Mountains that had held him for centuries. Unable to escape the prison due to blood magic seals forged by Malcolm Hawke, Corypheus resorted to using his powers to influence his Grey Warden jailers as well as a group of Carta dwarves. When Hawke, a child of Malcolm, arrived in nearby Kirkwall, Corypheus used the Carta to lure Hawke to the prison in order to break the seals. Corypheus was freed and promptly killed by Hawke, but the magister had the regenerative capabilities of an Archdemon and was able to escape by possessing the Grey Warden Larius or Janeka.

Corypheus spent the subsequent years preparing a plan to both restore the Tevinter Imperium to its ancient glory and return to the Black City so that he could claim the Maker's throne and become the new god of the world. Fortuitously, Corypheus acquired the Orb of Destruction, a powerful magical artifact, from the elf Solas, giving him the power necessary to bring his plan to fruition.

As the Mage-Templar War and later the Orlesian Civil War raged in the background, Corypheus began to assemble an army with the intention of conquering southern Thedas. Allying with the Tevinter-supremacist Venatori, the magister used his powers to deceive the Grey Wardens of Orlais into believing they were experiencing the Calling and were about to die. Desperate to find a way to kill the remaining two Old Gods before a new Blight could erupt, Warden-Commander Clarel de Chanson accepted the offer of Livius Erimond, a Venatori magister, to use a blood magic ritual that would create a demon army, thus bringing the Grey Wardens under Corypheus's control.

The Breach
Hostilities effectively began in 9:41 Dragon during Divine Justinia V's conclave at the Temple of Sacred Ashes, a Chantry-led attempt to negotiate an end to the Mage-Templar War. Corypheus and a number of Grey Wardens interrupted the proceedings. Justinia V was sacrificed to unlock the Orb of Destruction's power, and in that moment the Breach was created, rending the Veil between Thedas and the Fade. An unwitting witness to the sacrifice came into contact with the Orb and was branded with a magical mark called the Anchor, which could open and close the Breach and the numerous smaller Rifts scattered across the land. This would prove to be a major setback to Corypheus's plans, as he had intended to gain the Anchor for himself.

The lone survivor of the Breach was the individual who had been given the Anchor. Suffering from memory-loss and the Anchor's own debilitating effects, the survivor was recovered from the ruins of the Temple of Sacred Ashes and brought to the nearby village of Haven to recuperate for questioning by Seeker Cassandra Pentaghast and Leliana, the Right and Left Hands of the late Divine. Upon waking, the survivor was led to the Breach in the hope that they could use the Anchor to seal it; while the survivor lacked the power to seal it completely, they managed to calm it and stop it from spreading. Afterwards, the survivor was hailed as the "Herald of Andraste" and became one of the founding members of the new Inquisition, which Cassandra proclaimed in accordance with a writ issued by Justinia V before the conclave.

The events surrounding the Breach had far-reaching implications. The Divine and most of the Chantry's leadership were dead, leaving the Chantry leaderless and floundering. The leaders of the Mage Rebellion and Templar Order had also perished, reigniting the Mage-Templar War. Countless demons began emerging through the Rifts, terrorizing civilians throughout the land. Lastly, the Inquisition had been reformed with the goal of sealing the Breach and bringing whoever had caused it to justice.

Redcliffe and Therinfal
Despite losing the Anchor, Corypheus continued building up his army and planted the seeds of corruption within the Mage Rebellion and Templar Order. The surviving mages who attended the conclave retreated to the village of Redcliffe with the permission of Ferelden's monarch. The Venatori magister Gereon Alexius was dispatched to bring the mages into the fold; using time-altering magic, Alexius ostensibly rescued the mages just before they were attacked by a group of Templars and offered an alliance. Desperate, Grand Enchanter Fiona accepted, indenturing herself and her fellow mages to the Venatori.

Meanwhile, Lord Seeker Lucius Corin, leader of the surviving Templars, was replaced with an Envy demon loyal to Corypheus. As Corin, the demon widened the split between the Order and the Chantry by openly spurning Revered Mother Hevara at Val Royeaux, then regrouped the Templars at Therinfal Redoubt. There, the Templar officers were introduced to red lyrium and twisted to serve Corypheus as the Red Templars.

At Haven, the Herald of Andraste and their advisors Cullen Rutherford, Leliana, and Josephine Montilyet began to flex the muscles of the fledgling Inquisition by gathering allies and working to restore order. The Breach yet loomed in the sky, however, and it soon became evident that the assistance of the mages and Templars would be necessary to fully seal it. The Herald was presented with a choice: negotiate first with Magister Alexius at Redcliffe to gain an alliance with the mages, or approach Lord Seeker Lucius and the Templars at Therinfal. Both options held risks, as Alexius's requested audience with the Herald was obviously a trap, and Lucius's recent behavior and self-imposed isolation made him unpredictable.

Depending on whom the Herald decided to pursue first, the Inquisition conscripted or allied with the mages or Templars, depriving Corypheus of some of his forces. Contact with the other faction was lost; the mages at Redcliffe vanished with the Venatori, or the Templars at Therinfal became the Red Templars. The Inquisition learned of Corypheus's involvement, though knew the magister only as a mysterious individual called "the Elder One".

Attack on Haven
Returning to the Temple of Sacred Ashes, the Herald finally sealed the Breach with the aid of the mages or Templars. Although many Rifts remained and the Elder One was at large, the Inquisition believed the main threat was over. Together with the winding down of the Mage-Templar War, the Inquisition celebrated the end of weeks of strife and uncertainty.

That night, Corypheus led the bulk of his army, either the Venatori under Calpernia or the Red Templars under General Samson, in a surprise assault on Haven and the Inquisition to take back the Anchor from the Herald. The Herald rallied their forces and fought off the initial wave before using a trebuchet to trigger an avalanche that wiped out the bulk of the enemy host. Corypheus countered by unleashing his high dragon, which effortlessly broke and scattered the Inquisition defenses. The Inquisition and people of Haven fled to Haven's Chantry for shelter, but with what appeared to be an Archdemon on his side, Corypheus's victory was all but certain. Hope was restored by Grand Chancellor Roderick, who divulged the existence of a hidden trail from Haven that could be used as an escape route. Upon learning that Corypheus sought the Herald personally, the Herald decided to try and distract the magister long enough for everyone else to flee safety.

As the Herald fought another wave of enemies and redirected a trebuchet, the dragon attacked once more. Corypheus, revealing himself as the Elder One, arrived and attempted to remove the Anchor using the Orb of Destruction, but to no avail; the Anchor was permanently bound to the Herald. Frustrated, Corypheus decided to kill the Herald and start over, but the Herald triggered the trebuchet and started another avalanche, this one directed at Haven. Corypheus escaped with his dragon, while the Herald managed to reach the old tunnels beneath Haven before the avalanche hit. Making their way through the tunnels, the Herald eventually caught up with the surviving Inquisition forces in the Frostback Mountains.

The Inquisition had been dealt a serious blow and was in disarray. They were demoralized, had lost their base of operations, and feared the outbreak of new Blight, a danger implied by Corypheus's Archdemon-like dragon. Encouraged to take the lead by Revered Mother Giselle and the apostate elf Solas, the Herald guided the Inquisition through the mountains to the abandoned fortress of Skyhold, which became the organization's new headquarters. For their contributions, the Herald was formally honored with the title of Inquisitor, the leader of the Inquisition.

Investigating the Grey Wardens
As the Inquisition recovered, the Inquisitor's attention turned to the recent disappearance of the Grey Wardens of Orlais. Brought into contact with the Champion of Kirkwall, Hawke, the Inquisitor was informed that Corypheus had the power to manipulate Grey Wardens and imitate the Calling. Fearing that Corypheus had already done so, the Inquisitor followed the Champion to meet a Grey Warden in Crestwood (Jean-Marc Stroud, Alistair Theirin, or Loghain) who explained his fellow Wardens' were indeed hearing the Calling and had committed to a blood magic ritual designed to prevent future Blights.

The Inquisitor, Hawke, and Hawke's Warden friend traveled to the Western Approach, where the other Wardens were carrying out their ritual under the direction of Magister Livius Erimond. Unbeknownst to the Wardens, the ritual bound the demons created by the Wardens' sacrifices to Corypheus, not themselves; Erimond had deceived them as part of his master's plan. When the Inquisitor exposed Erimond at Adamant Fortress, Warden-Commander Clarel de Chanson and others came to their senses and turned against the Venatori. After the battle, the Inquisitor had to choose between allying with the remaining Grey Wardens or exiling them from Orlais for their actions.

Intrigue at Halamshiral
With another of Corypheus's plans foiled, the Inquisitor next had to deal with an assassination plot against Empress Celene Valmont I of Orlais, a plot uncovered during the events of Redcliffe or Therinfal. Unable to communicate by letters with the Empress at her Winter Palace at Halamshiral, the Inquisitor traveled to meet her in person during a ball being held as a cover for negotiations between the Empress and Grand Duke Gaspard de Chalons to end the Orlesian Civil War.