Excerpts from "A HISTORY OF THE ARCHCLERICY", 1365 DR, by Ashlar of Selgaunt.
 

1270 - Iuz and Zuggtmoy secretly establish the Temple of Elemental Evil in the Prime Material Planes of The Forgotten Realms and Greyhawk.  Iuz plans to gain followers in both worlds and use the Temple as a means of transferring power.  Iuz also intends to establish himself as a deity in the Faerunian pantheon.  Four Nodes of Elemental Evil are created on the Elemental Planes and connected via Gates to the Temple.  The Orb of Golden Death is created to augment the power of the Temple.

1272 - St. Cuthbert learns of Iuz's plan and begins recruiting followers in the Forgotten Realms, particularly in Cormyr.

1270s - Both Cuthbert and Iuz rapidly gain new followers. A cleric of Cuthbert, Titus, begins preaching in Arabel against evil (Iuz in particular).

1280s – The secular ruler of Cormyr (King Azoun III) is gradually corrupted by Iuz. The Government shifts from Lawful Neutral to Lawful Evil.

1283 - Azoun III launches a major persecution of the followers of St. Cuthbert.

1285 - Iuz vanishes, leaving his priests without high-level spells (In the world of Greyhawk he is imprisoned).

1287 - Archcleric Titus leads a revolution against Azoun III, winning control of Arabel and the north. Much of the Cormyrean army defects to the Archcleric. A palace coup in Suzail results in the disappearance of Azoun III, the ascension of his son Rhigaerd II, and the Government shifts back to Lawful Neutral.  However, Cormyr is now divided into the Archclericy (Lawful Good) and Royal Cormyr (Lawful Neutral).  Royal Cormyr consists of the southern coast, Suzail, and Marsember. The Cormyrean navy remains loyal to King.

1289 - The Archcleric preaches a crusade against the center of Iuz's power, the Temple of Elemental Evil (located along the eastern border of the Archclericy). The masses are exhorted to give their "Coppers for Cuthbert" and a large army is raised. Royal Cormyr announces neutrality.
 

1290 - Archcleric Titus leads a crusade against Temple of Elemental Evil.  In the first engagement near Hommlet, the humanoid followers of Iuz are routed.  The Archcleric's forces then advance and besiege the Temple.  The second battle results when demonic forces attempt to break the siege. (In this battle, the Banner of St. Cuthbert is lost).  In spite of severe losses, the Archcleric's forces defeat the demonic army and sack the Temple.  Zuggtmoy is imprisoned in the lowest level of the Temple.  Great wealth and treasure is gained.

1290s - Relations between The Archclericy and Royal Cormyr settle into a state of icy correctness.

1306 – The War Wizards organization is founded in Royal Cormyr as a counter to the priests of Cuthbert. In response, only lawful good mages are allowed to practice in the Archclericy.

1312 - Teziir is founded by Royal Cormyr as a naval base on Dragon Coast.

1326 - Death of Archcleric Titus.  Vidicar elected as second Archcleric.  With Iuz seemingly banished, Vidicar's long reign coincides with a steady decline in fervency of the Cuthbertian religion and increasing weakness and malaise of the Archclericy.

1336 - Azoun IV ascends the throne of Royal Cormyr.  He appoints his friend Vangerdahast as Royal Mage.

1338-1340 – The Dragon Coast War. Under the guidance of Vangerdahast, Azoun IV conquers Elversult, Ilipur, Pros, and Proskur to solidify control over the southern caravan routes. Yearly tax revenues of Royal Cormyr are quadrupled.

1350 - (Iuz freed from Castle Greyhawk).

1351 - Iuz begins rebuilding the Temple of Elemental Evil covertly. Nulb swiftly falls under his control.  The Gates to the Elemental Nodes are re-activated.

1352 - Iuz establishes a secret temple in Suzail. Vangerdahast (who has been corrupted by Iuz) begins planning the Second Cormyrean War. Azoun IV is reduced to the status of a puppet ruler.

1353 - Iuz gains the allegiance of the Demon-Prince of Evil Elemental Fire (Imix) and constructs strongholds near Skull Crag and Eagle Peak.  The cleric Kutos is placed in charge of the Eagle Peak stronghold, with orders to subvert the town.  Imix rules the Skull Crag stronghold.

1354 – Iuz (through the Demon of Fire) enslaves the Anubi people and their Pharaoh.  Each Anubi must wear a Torc of Fire to enforce obedience.  The Grand Vizier, Primax, is forced to lead a contingent of Anubi mages and warriors south to serve Kutos.

1356 - Iuz establishes the Temple of Evil Chaos in the Shunned Caverns near the Keep on the Borderland. His goal is to unite the goblin tribes of the Stonelands under a single leader, the Hag of the Shunned Caverns.  Iuz provides magical assistance to the Hag but cannot fully control her actions.

1357 – The Flight of the Dragons results in the fall of the dwarven city of High Horn and its occupation by an evil black dragon.  Giselin and the other dwarven survivors are scattered throughout the Realms.

1358 - The Time of Troubles in the Forgotten Realms.  St. Cuthbert descends to Arabel and shields the city from harm.  After St. Cuthbert's departure, Archcleric Vidicar lapses into despondency.