Before the birth of the Demon Queen and her subsequent changes in regards to their region and structure of control, operated normally as it would in any other military, may it be the Elven tribes and their Santa Gloriana Army, or the Humans with their various militaries on the Krischka Continent.
The Demon Generals of then were just generals that lead legions of Demons, rarely touching the battlefield as they were in charge of supervising the management of logistics and men throughout their continent Demios, more specifically the regions that they are in charge of. Since the dawn of the Demon Queen, an event named "The Blood Rain", there was a substantial change within the Demon military, and under the rule of this Demon Queen, a new order was formed that defied the rules set out by The Conglomeration, the government formation that united the different races of Veindeljara in an effort to avoid wars and to resolve political conflicts.
The Conglomeration was specific with regards to the taboo of summoning Deities that could harm the order they have set out to accomplish. Thus, only the Church of All remained, which at the time was worshipping the Crystalline Deity of Amethyst, Ameraan. Deity Ameraan would dictate certain actions that would lead the Conglomeration closer to their goals, however she would disappear a few months before the Demon Queen was summoned onto the Demon Continent Halbridge. The Conglomeration was quick to form the Coalition, a united force of races from Humans, to Elves to Golems and Goblins, and in response to this, the Demon Queen created her inner circle of Demon Generals called the "Eisenring Höllentruppe" which became synonymous to the term "Demon Generals" and were thus generalized as such.
The Eisen Hollentruppe is an elite group of Generals managed directly by the Demon Queen herself, these individuals control a vast majority of the Demon Army's arsenal and personnel. They carry about themselves at least 20 or so legions, however they have the authority to rally more to achieve their goal. These Demon Generals became the symbol of the Demon Army under the Demon Queen's ruling, and the Lesser Generals as they are now named held lesser authority among lesser legions within the army's ranks, making them little more than replaceable control towers for management of remote legions.
The system of control and authority has been significantly simplified, it is unknown why it has been structured like this but considering that the legions had been fed with more personnel from regions that had lost the Demon Queen's blood tournament, it can be said that the simplicity of the military structure was to manage region's worth of military personnel lead by the Demon Queen's Hand, the "Eisenring Hollentruppe", considered to be the Demon Queen's puppets by the Daemon Order, or what's left of it. (It is the Halbridge continent's version of a decentralized government before the Demon Queen's arrival.
Though, despite being considered as the elite of the elites, Eisenring Hollentruppe members were more or less forced to become a General under the Eisenring banner. This was due to the fact that they were individuals that represented a region in Halbridge in a brutal tournament to see who will serve the Demon Queen as her puppets. This meant that if one lost, the region would be either be subjected to genocide or be drafted into a legion within the army. These non-combatants would generally be lost as cannon fodder, or killed in action due to their experience, though, this allowed the Demon Army to have a sizable force compared to most of the countries under The Coalition, paired with the fact that those that were chosen to be in Eisenring were natural hunters, or generally prisoners that had extensive backgrounds of violence in their records, the Legions of Hell became a very effective force, regardless of deaths, and the amount of inexperienced fodder being sent out to battle.
Currently, there are only four identified Demon Generals in the field, it is suspected that there are more, an Elven General suggested that there might at least be two to four more that are unidentified by The Coalition.
Kalliope Taurturia
Status: Deceased
Kalliope Taurturia, commonly referred to by her wartime moniker "The Butcher". Is Eisenring Hollentruppe's Frontline General, she originally managed 30 Legions, but she had rallied 20 more from Hanagura to bolster her defenses against the Humans, 40 of which are currently engaging the Human Territory at the Continent Krischka, whilst the remaining 10 were sent to the Elven Continent Priscillica.
Her last recorded sighting was a direct attack onto Kingdom Fuhrenheim with a slew of mobile cannons, they were intervened successfully by an unnamed Adventurer Cell under Anahana's order. A letter was later sent by General Gladius that indeed, General Kalliope Taurturia of Eisenring Hollentruppe was indeed dead.
Another letter was received a few days after that the 10 Legions attacking the Prisillica Continent have been dealt with, with much ease. This unsettled the Elven General Lashrael who wrote the letter, and stated that there may be something else within their continent that may have been deployed to by a different Demon General to make up for the loses of Taurturia.
Other human kingdoms that were subjected to attacks from Taurturia's Legions noted that recession of attacks, and the uncomfortably easy counters to sieges from the Demons. These unsettled the Kingdoms but have given note to others that this may have been a sign of weakening forces.
Hanagura Gargia
Status: Ally
Hanagura is quite intelligent, her wartime moniker was the "Field Overseer" as her tactics generally revolve around the flexibility of her attacks. She was known to change into different tactics of combat midway through battles which have proved to be quite effective as it would allow her to confuse the enemy and thus make them more predictable. She had once control over 30 legions of Demons, but 20 of them were rallied onto Kalliope's, and when her death was announced by those from her fortress, she had no resources to attack or defend the frontlines as her remaining 10 legions were scattered on different points across the frontline that Taurturia had made. This to her was a failure to organize her legions properly and her over reliance to Taurturia's brutal tactics, which had left her base, the Roungkagare Tanaki, undefended. As far as the Demon Generals go, Hanagura is most sympathetic as she felt that the Demon Queen had betrayed her loyalty to the Daemonic Order (The Demon's form of a decentralized government)
There are news of Demons from Hanagura's legions sending aid to defeat stragglers from Taurturia's legions, there were some that had apparently sent a human FOB medical supplies and had stayed to protect the area from would be stray attackers. It is unknown as of yet if these Demons are to be trusted, as there has not been news from Anahana's group of their current situation.
Zakurello Hyuga
Status: Alive
Zakurello Hyuga was immediately identified as a priority target when she was identified to have been with Kalliope Taurturia. This was because Zakurello was a known prisoner as she managed to create a sort of mixed terrorist group against The Conglomeration, she was notorious for committing war crimes and subsequently planning assassinations and other such efforts to kill of those in the important seats within The Conglomeration in an effort to try and frame another country for assassination, or by outright trying to kill them in force.
It took the efforts of the Golems, Humans, Elves and the Demons themselves to subdue her lock her up. In the process, the Dark Elves had built a treaty with the Light Elves creating The Council Of Associates, an international council that was meant to thwart similar efforts that Zakurello had orchestrated.
Being nicknamed "Death Metal", after her Aura of absorbing and using metal as her main form of defense to thicken her skin, Zakurello was quick to attack Prisillica too once the initial attack from Taurturia was initiated. This seems to be the place where most of her forces were focused from, asides from the few legions that were found attacking the Golems in their nation of Obsidia.
However in the present day, Fuhrenheim and two other human kingdoms were informed that Kingdom Valurcina had fallen seemingly overnight, it was unsure whether Zakurello had changed her focus to fight the person that killed Taurturia, but the increasing sightings, albeit of small groups of her legions, indicated that it might be the case. Her whereabouts are currently unknown.
Ayamega Farguin
Status: Unknown
Ayamega Farguin was sighted only once in Kingdom Valurcina's territory besides what seemed to be a mix of both her Legion and Zakurello's. It is unknown whether Ayamega has reunited with her master, but the general consensus seems to be the case.
Ayamega Farguin, like Zakurello is also a terrorist before the war. Ayamega was notoriously known for bombings and her Aura of necromancy. Her group was restricted to mostly skeletal carcasses and Death Walkers, a kind of summon that kills anything onsite at the behest of their master. However it was a concern that Ayamega was identified besides legions who were identified to be Zakurello's as Ayamega had personally fought and was defeated by Zakurello. There were rumors that Ayamega has surrendered to become Zakurello's disciple when she was sent to Halbridge's maximum security prison where Zakurello resided, if they are proven true, then there are currently two high profile terrorists that are actively participating in the war. There isn't much information gathered on Ayamega as she has remained hidden somewhere, but it is known that she is relentless with her attacks, as it is evident with the fall of Kingdom Valurcina.
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It is unknown, and there are efforts to try and send spies to Halbridge, but there seems to be two or four more Demon Generals in active participation within the war. The presence of mechanical weaponry has been sighted in the frontlines being utilized by General Taurturia, and there were further sightings of more heavily armoured versions of these being utilized in the Obsidia Front.
With one Demon General killed, and another turning against the Demon Queen's Order, the sudden resurgence and increase of activity from both Zakurello and Ayamega's legions suggest that there would be an intensive retaliation to restore the Demon's frontline, however, with the spreading news of Yuriko Natsuki and Tatsuriko Anahana's active participation within the war to reclaim their land has created an uproar of morale within different surviving Kingdoms. Statrunheim, Kruskesch, Jalnofa and Granpero had begun their retaliation against the remaining forces trying to push out their frontlines to provide better defenses.
With how things stand, the Humans, and the Elves trying to defend their homes, and the Golems and the Goblins giving aid against the incoming horde, it seems that there would be one obvious outcome whichever way you look.
There will be bloodshed.