Warfare in the Known Worlds
Some say that war never changes, and while perhaps that is true for its impacts - devastation, the toll on soldiers and their families - it far from true for its methods.
The purpose of this work is not to lay out the specifics of mass combat. It exists solely to give a sense of what large scale warfare looks like, why it looks that way, and the attitudes and beliefs that dominate the modern battlefield. Also note that space navies as well as surface navies have always maintained their own separate culture, and are not represented below.
Infrastructure in a Post-Apocalyptic Society
Fading Suns is a space fantasy game set in a universe where poverty is rampant and intellectual inquiry is actively repressed by a fanatically anti-technology Church and a guild structure that greedily hoards knowledge. For thousands of years the grasping corporations of the first republican and the efficient machines of the Second Republic swallowed planets worth of resources and converted them into consumer products. The Empire in the 50th Century occupies the remnants of that society, surviving as best they can until the suns ultimate fade away into nothing.
That is the environment in which war is fought and as a result, war in Fading Suns does not look like what the average person might expect for a far-future society.
In Urth's 20th century there was a vast interconnected web of infrastructure, production, and industry that supports warfare at even a TL3 level. During America's Civil War, the Union was considerably outmatched (in many battles, anyway) in terms of the competency of the leadership and officer corps, as well as the South possessing at least as competent and motivated soldiers. Yet the South lost. Part of this had to do with simple attrition, but a huge part had to do with infrastructure. The North had a network of railroads that connected production centers to industrial factories that churned out everything from uniforms to condensed milk. Ammunition was processed from chemical refineries that in turn were connected to mining operations and all of it was shipped down along railways to the front lines. As blockades and the lack of production capabilities left the South starving, in tattered clothing, and without weapons and munitions, the North received resupplies and reinforcements from New York within days of them being made available.
No part of this infrastructure exists in Fading Suns. What mines there are have been tapped nearly dry, making mining the meager resources that remain a dangerous task suitable only for slaves or expensive equipment. With so little raw materials there is little call for giant industrial production lines- small factories produce bullets in limited quantities not for lack of demand but for lack of supplies. The only mass-produced rifles are the Imperial weapons carried by the Legions, and the supply chains required to equip a legion is a modern innovation that the Emperor, the Imperial Navy, and his military are struggling with. It is not uncommon for Legions in far flung parts of the Empire to run low on canned meat-substitute and be forced to scrounge.
What is true of supplying men is double true of supplying equipment. Consider that most equipment used in warfare today is customized technology- the environments and conditions that military hardware is meant to operate means that off-the-shelf, or mass produced, parts and replacements are rarely used. Replacement parts, originally produced in a Second Republic factory, must be recreated by hand from original drawings. Considering the time for such manufacturing, coupled with the shipping time and cost, the actual operational time of a hover tank on a distant battlefield can be as little as a few days out of every month.
Principles of Warfare
Certain principles have developed in this environment. The first is that any army that can supply itself from the land is preferred to one which can't. Without railways or in many places decent roads an army on the move cannot rely on food, ammunition, or even appropriate clothing to arrive when needed. An army which can make its own munitions (such as arrows or even musket balls) is preferred over one that relies on munitions which may arrive a day after a critical battle. All Imperial legionnaires are trained in how to use their rifles as a spear phalanx for when the bullets run low. Most armies are equipped with swords, maces, shields, and spears for this reason- a sword never runs out of ammunition.
The second principle is that when the machinery of war is necessary, whether it be tanks, artillery, or aircraft, cheap and low tech is typically more effective than advanced and high tech. A skilled engineer or even a mechanic can jury-rig a cooling hose for a TL4 tank engine using supplies around a camp in order to get the tank back in the fight. A TL6 tank might stop functioning because the circuit board that transfers power from the fusion reactor to the electrical drivetrain shorts out, and there is no clean room in the trenches to fabricate a new one. An operational diesel tank is always more effective than a non-operational hover tank.
There is also a second reason for the 'simple is better' rule. Armies are rarely uniform- a phalanx of spearman may have a few members with single-use anti-aircraft weapons, some of which might be highly effective even against advanced aircraft. Bombing a phalanx with laser guided munitions is incredibly effective, but if that phalanx has a chance of destroying your advanced warplane in return the cost/benefit quickly turns. If, however, those anti-aircraft weapons are expended on relatively cheap TL4 wood-and-canvas aircraft, the loss to both sides equals out. This is true of tanks as well, as IEDs and crude land mines have been known to cripple hugely expensive war machines.
The third general principle is that it is hard to predict what the opposing army is equipped with. Perhaps they are equipped with high tech anti-aircraft weaponry like above, or maybe they are completely vulnerable to the air. The wall of swords men might be easily gunned down by machine guns, or their shields might be coated with ballistic resistant polymers. That cavalry your tanks are chasing through the hills might be decimated once you get a clear shot, or they may turn blaster rifles on you and melt your tank's armor. House Decados succeeded in many of its battles not by having a superior force but by knowing their opponent's weaknesses. The same is true of the Hazat, who rely heavily on their Archons to pass information back to their commanders.
The Noble Army
Maintaining a standing army is beyond the financial ability of most nobles short of a Marquis, so armies are formed during the campaigning season on an ad hoc basis. Most minor nobles form a military by telling their knights and baronets to gather up some trusted armsmen from their villages and farms. Combined with the personal guard of the baron and perhaps a war machine or two that the noble maintains as a point of personal pride, a lord will roll onto the battlefield with a troop of mountain armsmen who may not have fired a gun in a year, several knights as officers, a gaggle of armed squires and serjeants, and the lord himself riding atop an old but well maintained tank.
It is also worth remembering that noble militaries are lead by men and women who may have had no formal training in warfare (for indeed there are few schools that teach it). They are, however, men and women raised to believe in the Pancreator-derived right to lead- thus society expects even the most ill-equipped noble to lead their troops (even if it is just from the command tent miles from the front). A fit, healthy noble who hands over command of his troops to a (admittedly more competent) muster commander is, in the eyes of his peers, only a marginal noble.
So what do all of the above combine into? In short, a mess. A Count or Earl might call upon his barons to prepare for war, at which point they call up their forces. In a field this gaggle of randomly equipped and irregularly trained forces start to muster, forming into companies and battalions in as organized a manner as the officers, mostly knights, can manage. In a field tent the Count and his council of peers lay out broad battle plans and assign roles to the barons (usually with each lord vying for the roles where either the most personal glory or wealth is to be acquired). From there the degree of organization, the utilization of the forces and resources, and the overall effectiveness of the army as a whole relies on hundreds of factors, but most of all the egos of the people involved.
Different Noble Houses obviously have different cultures, and ego being the dominant factor in warfare means that these cultures are going to shape what a military looks like. House al-Malik takes a great deal of pride in the guild contacts and high-tech connections. Despite being one of the early leaders in the Emperor Wars, they eventually realized the difficulties of maintaining these forces in the field and dropped out, instead relying on these tools for defense where supply lines were not as crippling. House Li Halan, the most traditional and least adaptable of houses, had trouble understanding the third principle above and suffered at the hands of the Decados, as the Mantis exploited House Li Halan's failure to diversify their military. House Hazat, with its military tradition, relied heavily on the extensive martial training of a core of its peasants, only to find as the war dragged on that it could not continue to maintain its highly trained core of soldiers with so many losses accruing on the battlefield. House Decados made excellent use of hordes of ill-equipped and ill-trained soldiers coupled with aggressive intelligence gathering on the enemy to ferret out weaknesses. House Hawkwood, more than any other House, abided most closely to the principles above- regular training of peasants allows for at least marginally disciplined armsmen to take the field, while the few high tech tools of the Hawkwood, such as the hovertank, were deployed as strike tools and not for maintaining the battle lines.
There are a couple of special exceptions worth mentioning:
The first is the Muster. People hire the muster for a variety of reasons, but the key is this: predictability. The Muster bring a predictable level of skill, training, and discipline to the table. Whether a noble is hiring a muster sergeant to lead a squad of men or a full muster squad or even platoon to supplement his own, the muster will bring a level of professionalism to the battlefield that a noble can rely upon.
The muster are trained with a variety of weapons but most are equipped with semi-automatic or assault rifles with the occasional squad or fireteam armed with submachine guns, lasers, or even blasters. The focus on firearms and their use means that the Muster are very effective if properly supplied, but quickly lose battlefield utility when on extended campaign. Thankfully the Muster are a one-stop shop, and the Muster have an entire division dedicated to trucking in supplies to the front. Of course, all of this comes at a price, and there need to be supplies to be had in the first place. Muster often find the prime contracts at the beginning of the campaign season, but by the end are forced to work more per diem jobs.
The second group worth mentioning are the Brother Battle. The Brother Battle do not merely train for a life of battle, they live inside it in a way that is not duplicated by any organization. For every Brother, combat for the Prophet is the Prophet attained. There is no organization which matches the Brother Battle in training, in tactics, or in discipline. The core of the Brother Battle consists of men who stare down shapeshifting monsters on Stigmata and do not flinch. If soldiers are capable of achieving an objective, the Brother Battle will achieve it. With the aid of theurgy, sometimes they achieve the unachievable. Well financed by their banking interests, well supplied by their auxiliaries, the Brother Battle are limited only by their very small numbers.