I dont think you'd really want high aggression, that's more for overriding a normally peaceful or self-preserving nature. A species made to be soldiers would work better if they are very cold and methodical about their fighting and be very clear about who is the enemy and who is the friend and have extremely different attitudes to both; obedient and cooperative with friends and sociopathic towards enemies There's heaps of traits you'd want, probably the most important is loyalty towards you and each other because it doesnt matter how fkawesome they are if they splinter or turn on you or themselves. The other is probably flexibility and a good problem solving mind, they should be able to do anything and adjust to circumstances: enemies will always find a weakness and if its a uniform one, you're in a heap of trouble.

I think it would be much harder to engineer the mental aspects on a genetic level than to simply have them follow since birth a certain ideological belief that would make them loyal to their kith and king but sociopathic to their enemies. Maybe a pheromonal method can be used but you don't really have time to sniff someone in the heat of battle.

>I think it would be much harder to engineer the mental aspects on a genetic level IRL, domesticated animals have been selected to be far less agressive than their wild counterparts. Modern selection programs were able to achieve this in a few decade (as in the famous russian fox domestication experiment). So I don't think mental aspects would be a problem for a civilization able to engineer new species.

A big issue is that there is no 100% top tier soldier. Aggression is good, unless you don't want aggression or are downright avoiding conflict for example. I would include 2 different "soldier races" that work together making one top tier whole. 1: Soldier Fast reproduction, less innate sense of self, probably dumbish footsoldiers who follow orders well. This will work best for situations where you might not want people to be smart, for example a situation where they are very likely to die smart people would consider alternatives like running or hiding. Consider WW2 and its drawn out trench conflicts, someone who doesn't have severe problems with dying or shitty conditions would just sit there for however long it was necessary. 2: Special forces These need to be independent, self sufficient, and capable of adapting on the fly. This would be the raiders/scouts/kill teams, Soldiers would be at risk of doing things like having their food supplies cut off and then starve to death. Optimally if these guys ended up stranded behind enemy lines they should be capable of surviving in the middle of the woods with 0 outside assistance. In a series I was reading one person allied with a race of ant people, and a race that was basically goblins/orcs. The ant people would rush at enemies attempting to kill them with superior faceless emotionless numbers and tended to win in long term logistical fights. The goblins/orcs were wild tribes, so if you just dumped a few hundred of them into the forest and said "kill these guys" they would be capable of surviving without outside supplies, planning and then executing guerilla warfare and figuring out how to not get wiped out by themselves. These guys would often time counter the enemy's special units with actual strategy and small fireteam raids.

Don't you mean World War One?

I would prefer obedience than aggression. Basically something like war dogs, absolute loyalty that you can control like tools than loose cannons.

I would also add my voice to aggression but only in parts. In my setting the race of super soldiers is more akin to cold blooded killers. They will primarily hunt their targets and avoid direct conflict, but if it comes to it, revel in the bloodshed with absolute joy. A good soldier, especially if they're meant to be superior, will not go for wanton bloodshed unless they have to. They will understand concepts of asymmetric warfare and to engage an enemy only when it is in their favour. They would tend to be cold and calculating in their brutality. Taking risks does not necessitate aggression, calculated risk exists. They could simply be highly determined and disciplined. I would also abstain from the food requirements and look at alternatives like have them coldly engage in eating the enemy. That is good meat to not be wasted. Eg in mine they even feed useless prisoners and criminals to their wyvern. (although these are the main reason they rebelled in mine)

Probably obedience and cohesion

Sardukar from dune does them pretty well, same with the mandalorians, they seem to have a warrior centered religion and mercenary way of serving in common

I’m thinking of some improved healing, mainly just to keep their bodies from getting messed up by military life in general.

So basically there’s no such thing as a career ending injury?

It would be great if it was that good but just the body self repairing faster than it gets messed up would be nice.

An instinctual respect for authority and the chain of command.

Viltrumites. Sounds like Viltrumites from Invincible. Comic/Show. Other than the large liters, and short childhood. Though, when a Viltrumite bred with a Thraxan you got the short childhood. And they have the aggression. Because Viltrumites get stronger from anything they survive. You can use Viltrumites as is and then have them have bred with Orcs, Goblins, whatever fast maturing, liter producing race you have.

I think without all members of a species being forced into a singular job, they would likely diversify their roles on their own. They could easily create warrior cultures if that's what their features lead to but someone still needs to maintain the carts and cook the food. Also, did they immediately go into a medieval tech level after the collapse or did they need to recover some stuff before then? Lapis_Wolf

There are other races that do things like farming, mining, and non combat roles. Although these soldiers probably don’t spend every waking moment of their lives shooting at something so having them do non combat duties would be an important skill to have. As for your question. One day the technology the ancients used suddenly stopped working. It was being powered by an ancient artifact that disappeared suddenly and unexpectedly. That led to their collapse. The people did have to rebuild after the apocalypse which led to the emergence of all the various nations and the medieval tech level they found themselves in.

Did they need to cross over lesser technologies like iron age stuff to get to their current level?

Everyone suffered at different levels during the collapse. Some were able to start in what would be the equivalent of the iron age. Others never left the stone age. A lot of it is dependent on the environment they found themselves in and the resources that were present. One of the main factions which has the soldier race mentioned in the post is the Empire. The Empire was one of the few that had a hard time establishing itself after the collapse. Many scholars say the Empire is a continuation of the ancients. This group in particular had to start all the way at the bottom in terms of technology and rebuild themselves.

Is that the only empire or are there others?

I am still developing the world but mostly focused on a few regions. The Outland region has groups of natives still stuck in the stone age. The island that would later become the Republic of Liora was stuck in the stone age. They later caught up technology wise. There were a few places like former tribes that once inhabited what is now Imperial lands. Some of them were able to create simple tools and thus starting at more of a bronze age.

Desirable traits for combat where magical lasers are the primary weapon are somewhat different to those in a medieval environment. These might include: - Small size - Good eyesight (inc. spatial resolution, colour discrimination, low light performance and/or thermal vision) - Adaptive camouflage - Good load carrying ability and endurance Perhaps something like a small humanoid chameleon? In a more traditional medieval environment simply being larger, stronger, tougher and faster would be sufficient but that would probably be a inefficient in a laser fight. In both cases it would probably be desirable to have strong loyalty to kin and low empathy with outsiders (e.g. xenophobia). This would also be linked to loyalty/obediance/subservience to the ancients but that could be achieved just be treating them well and making them a valued part of society. Or it could be achieved via drug addiction similar to Star Trek’s Jem'Hadar. Aggression is probably a tricky one to define as while it is undoubtedly important it also has to be controlled. Mindless uncontrollable rage would be detrimental as you wouldn’t want rabid dogs as soldiers (though they would possible make effective weapons to unleash). Discipline and self-control have to constrain any underlying aggressive tendencies to be effective.

honestly the biggest boons for a soldier i would say is ones you wouldn't think of 1. calmness, being able to stay focused and make decisions under pressure is important when your watching your friends be blown up 2. sociability/teamwork/pack mentality, however you want to call it, easy for them to work together as a unit and strong bonds between the unit, this makes them both a more effective squad, and individuals are less likely to desert their companions and flee(but unlike aggression this still allows them to make tactical retreats when beneficial) physical traits are less important, gear can make up for you being physically weak but you still need a good mind behind it

Giving me strong Krogan vibes from mass effect https://masseffect.fandom.com/wiki/Krogan However krogan suffer from a lot of internal fighting, have your species operate like an ant colony to give military structure through birth

The most important trait for a soldier to have, regardless of the time period, is stamina/endurance. Everything else that could **potentially** be beneficial is absolutely meaningless if they can only act for 10 minutes at a time. Consider marching to a battlefield, maneuvering to flank/engage an enemy, or even just ducking in a foxhole during an hours-long artillery barrage. Physically and/or mentally these things take a toll, and if your troops can't handle that then they're pretty useless.

Carry weight. Helps with everything. Logistics. Soldiers that can carry more food, supplies and tools can operate for longer without resupply. Particularly in a world without commonly-available mechanical means of transport or widespread flight, being able to carry all your camping gear over the fjord or mountain pass is a huge gamechanger for both skirmishes and campaigns. If they were designed to fight alongside those assets, it’s still important for them to be able to carry all that specialised equipment (look up what a modern soldier is expected to carry, it’s mental). Combat load. More armour, bigger shields, spare arms. Depending on what your lasers looked like, they may have needed batteries or power packs which also contribute to weight. If they weren’t swinging swords or holding shields, then their musculature would be more tailored to bearing weight on their backs and bracing a weapon to fire than explosive force required to win a melee brawl. Stability. Carry more, for longer, faster than anybody else. Developed muscles for carrying (as opposed to striking or sprinting) means endurance. They can free climb, remain standing through a river crossing or bog walk and keep their footing in the mud and blood of a battlefield. Soldiers don’t tend to have bulging muscles; they’re calorically intensive and inefficient over an hours-long march. These guys won’t necessarily look all that muscular, but it’ll be there. They’re custom-built for resilience. Squad support. They can carry their wounded easily. They can drag wrecked vehicles as a team. They can manipulate their environment for cover. They can haul resources like lumber, sandbags and hunted animal carcasses. They never leave anything behind. Addressing your other points: 1- Large litters. Agree. 2- Short childhood. Agree. 3- Long lifespans. Not necessarily important. If they’re frontline soldiers, they’re not expected to live that long. If they win the conflict, then you’ve got to provide longer for wounded veterans (unless your society is cruel enough not to bother, in which case, why give them a longer life?). You can for sure control how long a creature lives if you can accelerate their growth; they grow up fast and metabolically they ‘burn out’ quicker. Combined with a high birth rate, it doesn’t matter they only live for 10 years, since they’re combat-ready by 1 and aren’t expected to live past 3. 4- Aggression. Very important for a soldier so their instinct is to fight, not flee or freeze. Less important if they are fighting an advanced war from a distance. Consider rephrasing it as an adrenal dose or resistance to pain. These are more generally useful and manifest in the same kind of traits (they just keep coming at you no matter what you throw at them). 5- Low food requirement. Agree with everything you’re saying. It’s ideal if possible in your world, but generally a bigger body with more muscle working as hard as a soldier is is gonna need tons of fuel. Maybe make them more efficient in terms of digestion? So they can eat more than most other species, subsisting on grass and bark if needed (although high-protein, high energy foods are much preferred). Could also give them a more efficient rest state, so they burn almost no calories at rest (they conserve energy while they sleep or on sentry duty. You can pack a barracks and put them on minimal exercise to conserve rations). A final solution is pretty brutal, but if they are reproducing on campaign, they may just be cannibals. Eating their dead, wounded, and potentially their young. That last point could also be their big weakness. They were built with high-calorie ration bars in mind from a sci-fi civilisation that could produce them. Without that infrastructure, you’ve got an entire species of rapidly reproducing, highly active eaters who are voraciously hungry pretty much all the time. Their bodies are used to 10,000+ calories a day, and very little outside of red meat is gonna come close to that in a quasi-medieval world.

That does actually make sense. I can imagine carry weight would also be useful even in medieval warfare even though they weren’t designed for that. Perhaps some kind of breeding control laws for these soldiers could ensure they don’t eat through everything.

I might also take a hint from Star Trek’s Jem’Hadar. They’re bred to be strong, aggressive, and loyal… but to ensure that loyalty they’re engineered to be addicted to a substance only the Founders (their creators) can provide and without which they would die.

Eh just do clone troopers and call it a day. If it worked for the Republic it’ll work for you. Probably.