The Anarchy

The Anarchy was a civil war and international military conflict in Western Ovaicaea from 1020 to 1025, which resulted in the widespread breakdown of law and order across the region. The conflict was precipitated by several local wars and incidents of civil unrest, culminating in the death of Emperor Owyn Arranis.
Emperor Owyn's premature death in early Harvestide 1020 plunged the empire into chaos. The expanded imperial bureaucracy and courts were unable to respond swiftly to a growing number of smaller, regional crises involving the empire-wide feudal baronage and their kings, as well as succession issues meant to be mediated through the court system. The breakdown in negotiations between member states in the Imperial Assembly prevented a unified plan of action or the proper disposition of the imperial army in the emerging Tethar crisis. Tethar, feeling abandoned by the Empire for many decades and in the grips of a tribal civil war, invited Gastrinian legions to occupy the country to restore order, then seceded from the Empire and signed a treaty of federation with Gestrin. Shortly thereafter, Gestrin launched a surprise attack on the Confessor Abbey and sacked it, killing or capturing most of the Sisters and students.
Within a month, Skyshroud also declared independence, and Lithuar was consumed by the Wilde Uprising, which would also lead to Lithuari secession in early 1021. Princess Rowan was elected empress by an incomplete electoral college, with much controversy over its legalit; a third of the electors were not present, and her election was by a slim majority of those that were. Many of the western kingdoms were at each others' throats, or on the brink of collapse from increased feudal warfare between local lords, peasant revolt, or threat of invasion from the newly-independent nations. Gestrin launched an invasion of Mocryae and occupied parts of the southern imperial border, with next to no effective response by the Imperial Army. With the Empire bisected, the eastern kingdoms of Tolossia, Ripania, Athuasua, Suatha, and some minor dukedoms and imperial cities, in conjunction with the substantial eastern imperial legions, supported the claims of Prince Octavius to the throne. Deeming the western institutions incapable to handle the growing crisis, the eastern states formed their own Assembly and elected him emperor. He brokered a truce with Lithuar and Skyshroud, recognizing their independence, and crossed the Tethar mountains at the head of an army with the goal of reconquering the Western Empire.
The war would drag on in multiple fronts for several years, as practically every side fought each other for dominance with no-one able to achieve a decisive advantage. With most castles and walled cities being highly defensible, much of the fighting devolved into a war of attrition, comprising sieges, raiding, and skirmishing between armies of knights and soldiers, as well as the more organized, professional armies of Eldunari, Skyshroud, and Gestrin, and the divided Imperial legions. These intermittent battles devastated the landscape, with civilian infrastructure put to the torch as a means of striking at an opponent's means of supply, leading to mass famine; the rapid movement of several armies across the region spread disease wherever they went, causing further innocent deaths. As the war dragged on, enemies became more and more bitter and merciless, with massacre and pillaging commonplace. By the time the war was over, the Empire of Ovaicaea had lost around a tenth of its population, and some cities were completely depopulated.