Bodies Upon the Gears (Lanthanide Horizon Loreposting)

Where//Who//Why

In the open plains where yellow-bladed grass feeds off actinic blue light, and in the vast cistern-cenotes, and under rains of killing-sigils, the machinery of the world bends men to its will. Firstborn hosts in VR headsets, bearing magnetic halberds and crackling railguns, march from their growth vats directly onto the points of Oasis swords.

Like clockwork, new Firstborn move to the front - the Host Parallel and their spring-cavalry, the fatal basilisk-symbols of the Host Affine, the Host Symplectic whose banners burn with lethal smoke. They do not fear death, they rarely sleep, they send neither scouts nor messengers, and when they need food or water, the ground twists to offer it up.

And this is not the only front - to the south, the greatest cities of the Oases line up their mechanized armigers and their thousands of conscripts to meet armies with painted faces, who re-emerge in vast number every few generations, somehow quintupling in population in a matter of days. Those they capture soon return, newly painted and perfectly willing to kill those who were their brothers barely a week before.

Between the two, the Oases scrabble for mercenaries - but all those they wish to hire have wars of their own. The nomad septs of the Navigators quarrel eternally between their three Assemblies, only taking short tours of Oasis service to rain airgun rounds from their flying vessels - and each tour comes at an exorbitant price.

The other option, the Gardener Clans, are locked in their own seasonal war with the pastoralist Walker-Herds - both reliant on the same hydroponics complex/poisonous fen for food, and both wary of abandoning their territory to fight a strangers' war.

Of course, none of these are monolithic - the painted men who die on the blades of augment-knights are only one faction, some Navigator sept-vessels have elected refugees from the Oases as their advising Select, and far from the warfront Oasis cities find other matters to focus on. Even the Firstborn, despite the voice in their head, are not all sent to war. Some live not in fortresses, but in gardens.

How//When

Standing armies are almost unheard of in the structure. Among Sustainers, Gardeners, or Walkers, you may find the rare wandering hero or mercenary band, but a vast majority of soldiers are temporary levies. You pick up a spear for a season or two to drive off a hideous machine or skirmish with your neighbor, then return for the work of planting and harvest. 

Navigators have a stable base of violent manpower in the form of the koryos - adolescents unprepared for the responsibility of full adult sept membership, and expected to hunt for glory like wolves. Great campaigns attract koryos in vast warbands, but even in times of nominal peace they burn and loot.

All four of these have a tendency for low-intensity "endemic warfare" - ritual escalation, duels between chosen champions, raids and reprisals, and more capture than death.

Aristocrats of the Oases may keep single-digit numbers of armigers in their patronage chains, who trade military service for gifts (including the gift of arms). These aristocrats duel among themselves, raising token forces of conscripts (those who are expected to provide military service only when necessary, and perform some more worthwhile task during peace) to supplement their striding paladins. In true war (and the Oases pursue true war - they respond to a raid not with a raid, but with a massacre, which confuses the hell out of just about everyone else) they form retinues of retinues, city leaders calling on their client-aristocrats who call on their clients, who call on their clients, all the way down. 

The Firstborn follow none of these rules. Their Hosts are meticulously organized, logistically perfect, and permanently assembled. It is this, more than their equipment, that leads them to victory.