Commonwealth of East Falglor
On the Commonwealth side, the leader of the East Falglorian forces was Duke Alastair Stewart, a distant cousin and trusted ally of Elspeth. Alastair was mostly granted the position by way of politics, but was sort of proven in battle, commanding a few peasant forces in the Splintering and putting down minor rebellions in the Commonwealth in the years leading up to the Eight Year's War. He was no military genius, but whatever he lacked he hoped to make up for with a cabinet of military advisors. Under him were a number of nobles who had remained loyal to East Falglor who brought their own personal forces and troops into the war with them, such as Viscount Cadoc Pugh, the noble in charge of the garrison of Westrock, and Earl Harold Acker, who was second in command of the Commonwealth Army in the West, who had earned his position through both connections and a victory against the Royal Army that had gotten him promoted to the position.
The Commonwealth had a medium sized army, mostly comprised of conscripted peasant levies. Their army was hardly equipped, counting on the peasants to bring most of their equipment while allocating most of their best armor and weapons to the personally commanded forces of some of the nobles. Because of this, the quality per quantity ratio was terribly proportioned, with a thin minority being well-equipped units personally supplied by nobles and a vast majority being undersupplied peasant soldiers. To supplement both the manpower and the quality issue, the Commonwealth often employed the use of Uthani mercenaries.
Of the nobles that stayed with East Falglor, a great many of them were loyal to the Commonwealth and had bet a lot on the alliance's victory, and as such they contributed heavily to the army. Many nobles used their own personal troops as elite units within the army, contributing their resources and wealth to help the Commonwealth out. Much distrust and scheming to take power did take place behind the scenes, but for the most part, the nobles did place securing a victory over West Falglor over their own issues and grievances with the government and each other.
City-State of Gal Agapito
The army of Gal Agapito was small, barely numbering five hundred, nearly 1200 with peasant conscripts. Their navy also had chunks taken out of them as some Admirals defected or deserted when faced with the fact that they were going to war with West Falglor. Regardless they remained the premier naval power in the alliance, and were fairly competent when it came to sea battles, winning multiple naval and coastal battles with the relatively underfunded Royal Navy. Their main naval commander was Admiral Alasne Marinelarena, known as the 'Leviathan of the South' for her ability and accomplishments in sea battles against the Royal Navy. She was raised to the rank of Admiral of the Fleets for her contribution in putting down the South Sea Revolt and her tremendous ability in putting down a number of pirates and other enemies of state on the sea.
When it came to the land forces, Captain Unai Otxoa was the commander of the miniscule forces of Gal Agapito. Otxoa was a prominent member of the city elite, and as such was given the title of Captain as more politicking than in regards to any actual military ability. In that regard he was an imbecile, forcing the army into unfavorable positions many times and relying heavily on faulty or outdated intelligence to make his decisions, without much a grasp on any of the fundamentals of warfare. He was reviled by many of the soldiers of the army and was not liked within both the armed forces elite nor the civilian elite.
Gal Agapito, with their manpower shortages, was one of the forefront customers of mercenaries, hiring entire companies to fight for them. By the middle of the war, nearly three quarters of their army were mainly mercenaries, giving all the downsides of having a predominately mercenary army.
Tomachi
Tomachi was no better than the rest of the aforementioned alliance. It itself was undergoing terrible internal stability issues. Tomachi itself was a state cobbled together by Alammaran conquerors who thought that lumping the entirety of the cultures together in a singular province/region looked good on a map. As such, throughout the Period of Chaos and much of the Falglorian Unification War they suffered from heavy infighting and weakness caused by continual uprisings and revolts. Each noble within the country had their own army and own chain of command, meaning that no one really knew what was going on and there was little coordination between forces.
While on paper Tomachi possessed the second largest army in the alliance, most of it were the personal armies of nobles, some of which either didn't see a point in fighting West Falglor, or sided with West Falglor in the war. Of the forces that did fight Falglor, most of the armies were heavily undersupplied and low morale peasants, with personal units of the nobility rarely taking part in the fighting, if ever. As such, they were rarely able to raise such a large army, let alone keep it together as a coherent unit for long periods of fighting.
Fervoni Holy Union
The Fervoni Holy Union was the main powerhouse of the alliance, providing most of the financial support needed for most nations to fund their armies and contributing their own forces to fight West Falglor. The Union was an established power, one of the main arbiters of military might during the days before the Alammar Empire, and even within the Empire it continued in its influence and authority. Post-Splintering it had emerged with a large army and much public support from a great number of local and foreign churches all across the world in spite of the decline of religiosity.
Coming into the war it had the largest army of the alliance and was the most unaffected by the Period of Chaos. The only real flaws was that the Holy Union didn't possess a navy of any kind and was geographically located in the north, meaning it couldn't bring their full forces to bear against the Kingdom of West Falglor, plus the fact that they had to pay a number of taxes to Uthan for the ability to march their troops through the Efil Pass. As such the morale for the Fervoni troops was often low, with few actually knowing why they were fighting.
In command of the Fervoni troops was Great Defender of the Armies of the Gods (more commonly abbreviated to just Defender-Commander) Siegfried Meier, who underwent all the different trials needed to assume leadership of the army, and had been approved by both a bare majority in the United Council and the Grandmaster. Siegfried might have also gotten his role because he was a former member of the Alammaran elite and had powerful family connections within the church and was only elected due to politicking, though that fact is up for debate. Regardless, he was a competent enough commander during the Eight Year's War, though a bit conservative and crabby with his manpower and resources.
Halfway through the war Siegfried died by sudden heart failure, dying before he could be rushed to a healing mage. Some suspect it was his older age getting to the Defender-Commander, others suspect it was West Falglorian assassination, others think it was The Cult of Zelial. In any point, he was replaced in the role of Defender-Commander by Siamak Hatami, who was actually very competent, though by the time he had been raised to a position of leadership, the war was already lost. Siamak came to the role by way of repeated victories under his command on multiple fronts, proving himself worthy in the eyes of the churches.
Kingdom of West Falglor
The Kingdom of West Falglor was a rising power in the south. It had inherited a plurality of the Imperial Army from the Alammar Empire post-Splintering, contained multiple key-resource and production areas, a large population, and favourable geography. Not to mention that the Royal Army contained some of the brightest figures on military theory in the world at the time, people like Harold Caxaton, who revolutionized military theory for the next few centuries, laying out a whole plan for an entire reformation of the Royal Army, its ranks, separation from the nobility, and the different avenues of authority based on merit, coming up with ideas that were ridiculously ahead of the time.
These plans and reforms, however, would be delayed and lobbied due to the nobles disagreeing heavily with being locked out of the military. These military reforms would be partially put into place, though nowhere near their full intended outcome by the time the Falglorian Unification War broke out. They would later be fully enacted and put into place by James the First during his campaign against the nobility.
The commander of the army when the Falglorian Unification War broke out was General Hegio Plautus, a former top military commander in the Imperial Army who had defected to rebel forces following the Splintering. To buy his loyalty he was made a Baron and given his own realm, which did accomplish its task of buying goodwill pretty nicely. Regardless, Hegio was one of, if not the most competent and best military leader of the entire war, utilizing new technologies, new strategies, listening to field commanders, even leading his troops on the ground in more than one occasion.
The Royal Army itself was heavily powerful on paper. Most of its men were veterans of the Splintering and the different revolts and uprisings that had occurred in the Period of Chaos, and their ranks were large enough to not need to hire many mercenaries nor levy a large percentage of peasants, meaning that their agricultural base could remain intact throughout the war and not suffer tremendously in a prolonged war. Their army was also very well equipped, West Falglor possessing a large amount of ore and smithies willing to turn that raw ore into weapons and armor for the Royal Army.
However, what was probably the most important advantage and advancement for West Falglor is probably their revolutionary strategy of incorporating mages into the Royal Army. The program, spearheaded by Lodema Hulle, a mage herself, sought to produce or train mages on a large scale and integrate them into the army. This proposal, devised just around nine months before the Splintering, was approved by the at-the-time governor and later King of West Falglor. While the program was in its infancy by the time the Falglorian Unification war broke out, it was more than enough for the legions of alliance soldiers who had little to no mages, leading to total West Falglorian victories in head-on battles. The program would evolve and grow as the war raged on. Lodema would later be named Captain of the Magic Forces of Falglor, and serve until her death.
While the alliance and different nations around the Continent did have mages fighting in their armies during this period, it was usually isolated incidents of mages volunteering to join the army rather than something so institutionalized like in West Falglor. Attempts to forcefully recruit large numbers of mages were considered, but rarely carried out due to the innate ability of said mages to just fireball whoever came knocking. It was deemed impossible to carry out, and many nations simply didn't have the public support or resources to integrate any large amounts of magic users into the military, so when West Falglor did it, word spread quickly, though many were uncertain of how Falglor actually carried it out.