The Adhyrian Civil War took place after The Splintering, when nobody agreed upon the identity of the successor of the long dead king of Adhyria. Many self-proclaimed princes rose up, claiming to be the true heir to the throne. Each was an influential character of their own, holding sway over their own spheres of influence in Adhyria. The provincial governor of Adhyria from before the Splintering, who could be looked to to mediate the conflict was an Alammaran supporter, having long been executed during the days of the Splintering. The situation continued to escalate, with princes gathering support and consolidating their forces for planned offensives, until finally, civil war broke out.
The civil war was split between princes, warlords, barons and other minor nobility who wanted independence, city-states, and everything in-between. Groups of bandits or other ne'er do wells flocked to Adhyria in hopes of establishing their own state in the turmoil. Many small counties or towns slipped from the grasp of the Kingdom in the chaos as civil war broke out.
Most forces were made out of peasant infantry, hastily conscripted men with minimal training and equipment, or impromptu militias. Most elite forces were the personal guards of noble houses, or knights. Mercenaries were often employed to fight to supplement the lack of skilled men. Gaj were used often on the battlefield, either as mobile command structures for commanders to give orders to soldiers, or as shock troops deployed to smash through enemy lines and break formations. Magic users were highly coveted, either to aid in combat or to help heal troops as medics on the back lines. Mages quickly realized their importance and often charged premium for battlefield use, making mages rare in military forces.
Proper weapons and armor were rare, with the warring states often penny-pinching to fund more important logistical problems, like food, or to buy more experienced and skilled mercenaries. Most weapons utilized by peasant infantry are often repurposed farm equipment, with actual weapons being rare or reserved for the more elite units. Continued supply shortages would continue to be a problem throughout the rest of the war for most sides.
Once the fighting began, it was clear that there would be no quick, immediate victor, and that the civil war would go on for a long time. Short term strategies were replaced by more long-term ones, seeking to increase legitimacy and develop the parcels of land belonging to the different sides to out-logistic the other sides. Resources were rationed and trade with foreign nations were often raided by other sides. Most of the smaller, less powerful sides were quickly subsumed by the more powerful princes and warlords, though a few continued to resist until the end of the war.
Results in the first few years were mostly inconclusive, with either no border changes or negligible ones at best. Each prince carved out their own sphere of influence, inside the former kingdom, seeking to better develop their portion. Nothing really happened for about a decade, until the outbreak of the Age of Frost. When the Coalition of Nations was first formed by The Order, many princes decided to not support them at all, seeing as they had their own batch of problems. However, the principality ruled by Cyakti Mahatva decided to take up the call, aiding the Coalition with supplies and soldiers. While putting himself at a heavy disadvantage initially (one that his enemies pounced on, taking many tiny undefended towns) this move won him the support of the Coalition as a potential candidate for the throne of Adhyria. The Coalition backed him, sending him gear, money, food, things he used to bolster his armed forces.
Eventually, Cyakti marched on his neighbors, taking them by surprise and demolishing them with speed, superior tactics, and better equipment. He quickly spread his banner all over the north to the west of Adhyria, leaving only a few weakened principalities left. It seemed that Cyakti would be victorious, and his line would be proclaimed the kings of Adhyria, until the Kingdom of Falglor intervened in the conflict, seeking to not prop up one of the leaders, but to conquer and either annex Adhyria or convert it into a protectorate. This lead to the Eastern Adhyrianus War, which Cyakti and the rest of the principalities eventually lost.
The Adhyrian Civil War eventually ended in a Falglorian victory, though Cyakti still benefited, being propped up on the throne as a puppet leader with a degree of power over his domain.