On War in Dungeons and Dragons

Introduction

Well, it seems that large scale war is a pretty common topic for people to ask about, and it creates a lot of interesting plotlines. Further, players – or, at least, my players at any rate – have a bit of addiction to it. Because I am a sad little man with nothing better to do with my life, I have decided to pontificate and expound about conducting war in Dungeons and Dragons at definitely and unnecessary unsolicited length. Enjoy!

The Role of Magic

Magic is an incredibly important factor in conducting combat in DnD, and has a massive influence on the field at every level, ranging from the typical adventuring party skirmish to clashes of large armies in conventional warfare. It seems to be something of a widely held opinion that magic renders armies without it entirely obsolete, in much the same way that an army today without aircraft is useless. However, I believe that magic is, in fact, not that important for conventional warfare. It is useful, undeniably. Well supported by other arms, it is battle winning. But I think of it is more as artillery in the 19th century than a nuclear bomber – potent and effective, but at the end of the day still another tool for a commander to use.
Now, I must make pains to point out that I am assuming a specific model of magic here, which is that 1% of the population can practice magic – of that, 1% of them are Level 2 casters, and 10% are Level 3 casters, and 10% of those are Level 4 casters. Anything more powerful is the province of adventurers and heroes of legend, not armies. So I am speaking from a very much low-magic setting, and the above assumption is obviously fallacious when talking about something more high powered – the Tippyverse being the ultimate example there, of course.
But, taking the above assumption of caster population numbers as accurate, we can start to get to grips with the number of casters actually available to an army. Take the estimated population numbers for High Medieval England – it’s about 5 million or so. That translates to 50,000 Level 1 casters, 500 Level 2 casters, 50 Level 3 casters and 5 Level 4 casters. Okay, so maybe not incredible numbers, but it still looks like more than enough to be a major army, right?
Not really. Firstly, there might be other services of the government which require casters – any constable or police forces (such as the beloved town watch) would dearly love casters, as even Level 1 spells provide a great deal of versatility– Charm Person and Alarm both seem pretty useful. Similarly, the customs agents, tax collectors and other assorted services would surely want their tithe. Furthermore, local lords and communities would certainly prize casters, both as status symbols and also as potent force multipliers in peace; see, for example, plant growth. Further, age enters the picture here – some casters might be too old or too young to go on campaign.
And all that aside, unless the country is running a purely command economy – a rather unpopular measure – then casters would surely be able to engage in their own acts of free trade, creating companies and business concerns. This would make them less available to government forces – and whilst they could be compelled, that might prove rather messy. Worse, Wizards certainly require specific tuition; so there is likely to be a number of Wizard colleges around the country, which require magical staffing. Moreover, there will always be those casters without direct combat relevant abilities or powers, and thus unsuitable for service in the military. Lastly, there are sometimes inherent biases against different sorts of people being in conflict; for example, would female casters be allowed to fight?
Whilst I can’t put exact numbers together for the final total of casters available to the army at any one time, suffice it to say that massive armies of mages are probably not on the cards for any nation state which doesn’t literally enslave every caster in their land (which would probably end with a rather bloody caster’s revolt). Therefore, under this model at least, magic is a force multiplier, not a battle winner.
Now, speaking of the specific utility of the spells that they could hypothetically use, I’m going to go through every cantrip, Level 1 and Level 2 spell for Wizards – whilst this does not cover every application of magic in combat; notably Rangers might be very impressive scouts, in particular, it gives a feel for the ideas that will be later raised for the employment of magical forces.

Wizard

Cantrips

•Acid Splash: 1d3 Acid Damage? Not useful, really. A bow can do it much better, with far less expense and at much less risk to the valuable caster.
•Blade Ward: I guess it’s useful for keeping the caster alive, but not much beyond that.
•Chill Touch: 1d8 damage against a single target within 120ft – sort of useful, I suppose, but it’s nothing an archer can’t also do much more cheaply.
•Dancing Lights: Incredibly useful. Communication was one of the major hurdles of medieval warfare, and the ability to send light signals – possibly varying in colour – is rather useful.
•Firebolt: 1d10 damage to a single target within 120ft – not bad, but not exactly incredible either. Perhaps useful for picking off enemy spell casters, commanders, musicians or the like.
•Friends: Useless for any in combat use. Perhaps useful for out of combat diplomacy – see foraging, later on.
•Light: Some limited utility in night battles, but a torch is probably easier to use en masse.
•Mage Hand: If you’ve got explosives under 10 pounds, then pretty useful – if not, not really. Might be handy for swiftly distributing caltrops or stakes in front of a formation though.
•Mending: Deeply limited utility on the battlefield – but an absolute godsend off the battlefield. With Mending, you can safely remove a lot of support staff from the baggage train of a convoy.
•Message: Super useful for conveying information up and down the lines of battle. One approach might be to create lines of Level 1 casters leading from the frontlines to a command/information post, to ensure very rapid, near real-time communications – although watch out for Chinese whispers!
•Minor Illusion: Super useful. This allows for incredible abilities at fooling enemy scouts and can also serve a useful midbattle role by sending false orders or signals to the enemy.
•Poison Spray: No, just no. 10ft range means that the wizard has to get very close to the enemy to be of any effectiveness with this. As a personal defence tool, sure – but never as a primary combat tool.
•Prestidigitation: Useless in battle, by design. Rather useful outside of battle, what with cleaning of clothes reducing disease risk significantly. Flavouring might be requisitioned by kitchen staff to make rations taste nice.
•Ray of Frost: Not that useful. It does damage comparable to a bow, and the slow effect isn’t that impressive when talking about the clash of large armies. However, one utility for it is when fighting closely packed ranks of men moving at a consistent speed; slowing one of them could disrupt the rest of the formation.
•Shocking Grasp: A wizard should never be in Touch range of an enemy if they can possibly avoid it. So no.
•True Strike: It could be useful in limited circumstances – for example, a line of wizard cavalry charging with True Strike active and then quickly disengaging. This will be covered later in the section of using magic effectively.

Level 1

•Alarm: Certainly some utility, both in protecting rear areas and in providing warning for infiltrating enemy forces.
•Burning Hands: Somewhat mixed. Whilst it is certainly useful as a way to smash apart a charge in one go, it does require the wizard to get close to the enemy. With Shape Spell, it’s definitely useful – otherwise, it has situational utility.
•Charm Person: It has some utility for interrogation, perhaps, softening up an enemy soldier, but otherwise little direct conflict usage.
•Chromatic Orb: It's a very solid attack at 3d8 damage - but the lack of AoE does sting. This may be best used for taking down monsters or large linebreaker style units (addressed later).
•Colour Spray: Suffers similar issues when compared to Burning Hands, but is also very useful for charging and breaking enemy formations, blinding the front rank and thus making them much less able to engage friendly forces.
•Comprehend Languages: If operating in a foreign area, this might help with foraging parties – it does, however, have limited direct combat use.
•Detect Magic: Possibly useful, I suppose, for identifying enemy infiltrators or those armed with magic weapons. Has a degree of utility in detecting enemy casters in the ranks, but that can be fooled.
•Disguise Self: Rather useful for infiltration, but that presupposes sending valuable wizards on scouting expeditions.
•Expeditious Retreat: Well, it’s certainly good for retreating, I suppose, and rather effective for the “wizard shock troops” idea, discussed below.
•False Life: Useful for wizards concerned about enemy assassination/counter-wizard attempts – it may keep them alive for a little longer.
•Featherfall: Certainly has some utility among air crews, and is a key point for paratroops, which will be discussed below.
•Find Familiar: A familiar has some pretty useful features – most notably, it makes an excellent short range scout.
•Fog Cloud: Excellent concealment and good way to create a pseudo-smoke screen in the face of archer fire.
•Grease: Really, incredibly useful. With this one spell, a couple of wizards can shatter a formation, by causing the soldiers in the targeted area to fall prone, disrupting the rest of the formation and impeding defensive efforts.
•Identify: Maybe some use for a pseudo Intelligence Corps, but otherwise pretty ineffective over all, especially considering cost.
•Illusory Script: Excellent utility for couriers and secure military communications – this would be a godsend for a headquarters.
•Jump: Excellent way of enhancing mobility for other soldiers, perhaps to exploit a breach made by a wizard unit.
•Longstrider: Useful for skirmisher units, as well as those called upon to exploit a breach in the enemy lines.
•Mage Armour: Useful for keeping other wizards alive, but most soldiers worth protecting should probably have better than +3 AC armour on anyway – skirmishers may not though.
•Magic Missile: Deeply ineffective at stopping mass ranks of enemy infantry, but may well have a degree of utility in sniping enemy command elements.
•Protection from Evil and Good: Unless engaging an elemental heavy force, this is really not worth it – and in any case, it doesn’t really effect that many people.
•Ray of Sickness: Perhaps good for sniping enemy command elements, but otherwise rather ineffective and too short ranged.
•Shield: Good as a desperation move, but nothing more really.
•Silent Image: Can provide rather effective cover and distraction against the enemy, but not much more than that.
•Sleep: Perhaps useful in a line breaking capacity, but the indiscriminate nature of the spell means it is not good for a unit working together.
•Tasha’s Hideous Laughter: Perhaps useful for raids and psychological warfare. Also great for hitting an officer or musician. However, it is painfully short ranged.
•Tenser’s Floating Disk: Could be useful for creating a little bit of top cover against archers. Also surely a godsend for transportation on rough terrain.
•Thunderwave: Useless for the line of battle – far too indiscriminate.
•Unseen Servant: Perhaps useful for distributing caltrops, planting stakes and dropping alchemical items on the enemy, but a short range and fragile nature makes it rather unimpressive.
•Witch Bolt: Useful for bringing down linebreakers and sniping commanders/flagbearers/musicians but deeply limited for mass usage.

Level 2

•Alter Self: It probably isn’t worth turning the wizard into a reasonably subpar brawler, and whilst it has potential for infiltration efforts, that would require committing valuable wizarding assets to very risky operations
•Arcane Lock: Has some utility in sieges and urban combat, but on the field of battle essentially useless, especially as it is rather expensive.
•Blindness/Deafness: Has a little utility for targeting officers or musicians, but otherwise somewhat limited – especially as it has a very short range.
•Blur: Purely useful for personal defence – which is sort of a desperation measure.
•Cloud of Daggers: Has utility for disrupting an enemy formation, but otherwise rather unimpressive. Can be used particularly, to barricade an enemy charge.
•Continual Flame: A little use for long-term night operations, and for ventures into the underdark. However, it is very expensive.
•Crown of Madness: Rather useful for disrupting an enemy formation, and reducing trust and unit cohesion, as each enemy soldier must be on guard against the possibility of their friends being crowned.
•Darkness: Perhaps useful covering retreats. Very effective at disrupting enemy formations. Whilst range might be an issue, imbuing an arrow or ballista dart with the darkness then shooting it into the enemy ranks might be very effective at breaking down command and control.
•Darkvision: A great degree of utility for small units, most likely scouts, working under cover of night.
•Detect Thoughts: Effective as part of an interrogation, but otherwise deeply ineffective on the field of battle.
•Enlarge/Reduce: Certainly has some merits, particularly in rapidly Enlarging shock infantry. Also quite useful for enlarging the third row back in a spear formation, so that more ranks can attack.
•Flaming Sphere: Excellent at disrupting enemy units, forcing them to scatter and thus be vulnerable to other attacks. The range is also very solid.
•Gentle Repose: Might have some utility if you want to preserve a corpse of a great soldier to revive, but otherwise not that useful.
•Gust of Wind: Superlative at disrupting formations – flank an enemy unit with this, and watch as their front ranks are smashed into a complete mess.
•Hold Person: Not really worth it; holding one person for up to a minute is not that efficient for unit disruption, and it is better to just kill enemy officers.
•Invisibility: Certainly useful for scouting in small groups – if able to be applied en masse, might have some validity for inserting a flanking force into the enemy rear.
•Knock: Useless on the field of battle.
•Levitate: Maybe levitate an explosive or other such payload above the enemy, then drop it on them?
•Magic Mouth: Could be useful for contingency orders, but inefficient for more routine communication.
•Magic Weapon: Possibly useful for the shock troops idea (discussed below) but otherwise a relatively inefficient use of a spell slot; unless you’re fighting incorporeal enemies on a regular basis.
•Melf’s Acid Arrow: Not a superlative attack, but not that bad either, It certainly has some merits insofar as sniping command elements or linebreakers goes, but it is ineffective at being used against enmasse infantry.
•Mirror Image: Certainly useful for the purposes of preventing the easiest counter-mage operations, although this might depend on the strength and ability of hostile snipers.
•Misty Step: Perhaps has some utility as a bug-out option of desperation, but every spell used to preserve the wizard limits their utility, so probably not.
•Nystul’s Magic Aura: Some utility in deceiving enemy mage hunters possibly, but again something of a waste; although making several permanent aura items and attaching them to ordinary soldiers might have a degree of utility.
•Phantasmal Force: Some utility in deceiving scouts, but frankly if you know a scout is there, then it is probably easier just to kill said scout.
•Ray of Enfeeblement: The fact it only affects one target is somewhat limiting. However, it would surely be effective against linebreaker units.
•Rope Trick: Perhaps for making a secure observation bunker, but little else.
•Scorching Ray: Useful for knocking out linebreakers and officers, but the lack of AoE really stings against mass formations.
•See Invisibility: There are cheaper ways of detecting invisible enemy assets, although I suppose it might have some utility for guard duty.
•Shatter: A useful AoE attack, and very nice for softening up an enemy formation prior to a charge.
•Spider Climb: Unless there are a lot of wizards in the army, then this is not that effective for anything other than reconnaissance or special forces operations. If there are sufficient wizarding assets, then this could allow for some rather impressive operations in mountainous terrain.
•Suggestion: Not worth it for anything other than interrogation
•Web: Cavalry charge? What cavalry charge? This single spell can reduce most offensive actions to a complete wreck, and is very possibly the single most useful weapon in the wizard’s arsenal.

The Roles of Magic in Combat

Okay, so having looked through these spells, we can see there are five basic uses for the wizard – and by extension, magic – in large scale conventional warfare. These comprise:
•Anti-Linebreaker Assets: Many armies would like to use large animals or monsters to smash through the friendly lines, allowing mundane troops to exploit the breach and slaughter the exposed rear echelons of an army. Magic provides an incredibly potent toolkit to deal with these enemy units, with spells which can kill them completely and spells which can entangle them or otherwise render them unable to pose a threat to the rest of the army.
•Suppression of Enemy Magic Assets: Magic is important in battle, in much the same way that artillery is. Therefore, a large portion of a caster’s usage in battle would be countering other casters. This can take the form of direct counterspelling, sniping enemy casters with things like Witch Bolt or Scorching Ray or locating hostile casters so that friendly archers can pick them off.
•Command and Intelligence: Message allows commanders to rapidly issue orders with the expectation of the order being received and implemented with a great deal of speed. Similarly, Dancing Lights can allow for messages to be passed up and down the line effectively even without direct Message lines. Therefore, there would presumably be quite a few casters on the command staff of various units.
•Formation Disruption: Level 1 and 2 spells really aren’t that impressive at slaughtering the enemy en masse. However, a lot of them are ludicrously effective at disrupting enemy formations and destroying unit cohesion. Grease could really knock over a phalanx, whilst Web will crush a charge, for example. A lot of the offensive use of magic assumed would probably in nerfing the enemy so hard that they cannot fight back effectively.
•Sniping: Magic is often rather accurate and can deliver impressive damage to a single target. This means that some casters might end up specifically sniping enemy command elements, signallers and standard bearers. This would presumably demoralise enemy troops and contribute heavily to the inherent chaos and confusion of the battlefield.

Formations and Deployment of Magic

Now, the idea of standing all of the wizards in a line and making them blast at the enemy is a bit pointless. I would contend that wizards – and casters more generally – work much better when paired with other units and mundane soldiers. This is for two key reasons:
•Force Multiplier: Low-level magic is not a god, it’s a force multiplier. Webbing an enemy squad won’t kill them, but it will make the job of allied foot soldiers much easier. Therefore, casters need to deploy alongside mundane troops to get the most killing power out of their spells.
•Fragility: A wizard or other such caster is inherently fragile in close combat, and is also a rather expensive asset. This means that it is a perfectly viable strategy to sic 20 or 30 mundane troops on every enemy caster. The killing power of low-level magic against mundane soldiers with a modicum of intelligence is probably not sufficient to actually stave off this sort of offensive; but a squad of plate armoured footmen could do the job pretty effectively, especially if aided by magic.
Okay, so you probably can’t deploy them solo – then how would you deploy them? Well, in direct combat, I’d suggest four basic formations for the use of magic assets:
1. Anvil: This idea refers to seeding magic users throughout the main body of troops, so as to form a much tougher overall line of battle. Depending on rarity, each company (100 men) would have a certain number of magic users. They would be primarily focused on counterspelling hostile magic attempts and at using battlefield control to make the job of the mundane troops accompanying them that much easier. In a ranked formation, they would likely be in the fourth, maybe third rank – close enough to use a lot of their powers, but not so close as to be at unavoidable risk of melee combat, which would likely be rather bad for them.
2. Grand Battery: This idea refers specifically to the concept of casters as counters to linebreakers and other such monsters and “superunits”. It would essentially be a concentration of magical might with mundane troop escorts to stop them being overrun by a surprise attack. Terrain permitting, they might be mounted on carts or other such vehicles to allow for fast movement along the lines. When a major enemy linebreaker is spotted approaching friendly forces, Message lines would summon the Grand Battery into place where they could use their local concentration of magical firepower to swat down this linebreaking attempt, either through actually killing it or allowing the mundane formation accompanying them to butcher it.
3. Linebreaker/Heavy Cavalry: Well, I’ve talked quite a lot about linebreakers so far, and I’ll talk more about them later, but this is one example of a linebreaker unit. The essential idea is to have a mass of casters accompanied by experienced and effective heavy cavalry – knights, essentially. The combined formation would ride at the enemy, and then just before contact the casters in the front ranks would cast a variety of battlefield control spells; Flaming Sphere, Web, Grease and so forth to break the enemy unit coherency and stop reinforcements from flooding the scene, with other casters counterspelling as hard as possible to avoid an enemy Web or similar tripping up the entire offensive. Whilst it would take a lot of practice both for the casters to break off safely and for there not to be friendly fire with magic, it could be an incredibly useful tactic which ends up with the enemy in complete disarray.
4. Harasser/Light Cavalry: This formation consists of casters embedded in light cavalry formations. Their duty would be sowing havoc before conventional combat truly began – Witch Bolting commanders, Greasing slopes so that siege engines fall down them and smash, Webbing marching columns to destroy any hope of an orderly deployment. It would, however, be something of a high risk activity – most spells are very short ranged, and so the cavalry units would have to make excellent usage of cover and mobility to ambush the enemy.
Protecting Casters Casters are valuable assets, and would surely be targeted (see below) at every opportunity. Therefore, a sensible army would surely take precautions to avoid their casters being killed. Here are a few suggestions as to how that might work:
•Decoys: Having a few particularly brave soldiers stand in obvious locations and pretend to cast spells in sync with the actual spell casters doing so from a second, hidden position, would be a really useful way of stopping casters from being picked off.
•Bodyguards: Every caster should probably have a couple of mundane bodyguards in order to make sure they are not effortlessly killed by infiltrators whilst in camp. Alarm spells can certainly help with this.
•Aggressive tactics: The enemy can’t look for casters in your ranks if he’s too busy running away screaming whilst on fire and blinded, now can he? Maintaining offensive momentum and a high tempo of operations to throw the enemy off balance should be reasonably sufficient to distract him and make sure that casters aren’t discovered.
Countering Casters Well, with those defences in mind, how does one counter casters? Well:
•Have more or better casters: Counterspells work much better when you have more of them than the enemy has spells, for example. If you can maintain counterspell dominance, then the enemy magic assets end up pretty pointless.
•Adjust doctrine: A lot of the problems inherent to being under magic attack can be countered simply by assuming a dispersed formation and relying much more on ranged attacks and stealth than straight up close combat. There are, however, issues with this approach. Firstly, cavalry will sweep away that sort of formation pretty easily – though embedded casters with Web and Grease can cause quite a few problems that would require a lot of magical strength committed purely to defensive efforts. Moreover, most magical attacks require closing to rather close range and do not support sniping, thus taking most magical assets out of the game for offensive action. Thus, dispersed formation and counter-magic training is only one part of a wider solution, not a panacea.
•Kill enemy casters: This doesn’t refer just to engaging them on the field of battle – it also means finding them in tents in camp and killing them, or murdering them in peace time. Casters, as a rule, take a while to train and so murdering them outside of battle can be an effective and long-term counter.
Magic Conclusion Well, that wraps up this set of pontification about the role of magic in direct combat – there will be more about magic throughout the rest of the piece, but this is certainly the most concentrated it gets. I hope that I have proved both that magic does not automatically invalidate armies – at least at low levels – and that there are creative and useful ways to use magic without it being purely “line up and blast away”.

Financial Factors and Logistics

Finance

First thing – armies are expensive. Really, really expensive. The state has to equip, pay and feed their soldiers. It also needs to acquire the vehicles and animals to move them in order to facilitate this pay, food and equipment reaching the soldiers. Worse, the state also might need to deal with pension and healing costs. We know from real life examples that maintaining major wars can and did bankrupt entire nations, and it’s typical for the nation to be placed in heavy debt supporting a war.
Moreover, even if the war is won – which is certainly no guarantee – then the state must deal with demobilising its armies. This means taking a lot of men, some of whom might have been on campaign for years, with all the attendant physical and psychological difficulties fitting in to normal society, and placing them back into civilian life. This could easily lead to a spike in crime and banditry, as ex-soldiers can’t always find a job. Now, this can of course be alleviated by paying the soldiers a pension for their service; but that’s also very expensive.
Specific Costs/Building a Cost Profile
Alright, to get a handle on the costs of actually running an army, we’re going to “build” a soldier from the ground up, equipped for a 6 month campaign in foreign lands.
•Equipment: First things first, the soldier needs equipment to be able to fight in any capacity. Assuming a set of equipment somewhat similar to the late Roman military, he’s going to need a spear (1gp), a longsword (15gp) and a dagger (2gp) for weapons. Then, he’s also going to need a set of scale mail (50gp) and a shield (10gp). So that’s 78gp just for the weapons and armour. Then our soldier also needs a variety of other bits of non-combat kit, like: a backpack (2gp), a bedroll (1gp), a mess kit (2sp) and a whetstone (1cp). So just for outfitting one solider, one is looking at the minimum at a total unit cost of 81.21gp.
•Food: Soldiers, unsurprisingly, actually need to eat. Now, part of the food burden can be alleviated by foraging; but foraging tends to be somewhat of a bad idea in some circumstances, and in any case, campaigns in the territory of other races might be lacking in sufficient food to provision the entire army. Thus, a sensible planner would probably budget for the army to be self-supporting in the matter of food. The easiest way to do this is to buy Rations – one day of ration is 5sp. Therefore, for this prospective 6 month campaign, this single soldier is going to eat around 90gp in rations. This can be alleviated in larger armies by bringing livestock along with the force, and butchering them for food as the campaign progresses – but that carries its own rather large attendant risks and costs.
•Pay: Unless one is running a purely levy army, then the soldiers are going to need to be paid at some point, otherwise they might get a little agitated, and an agitated army is the worst nightmare for a state. The DMG for 5e suggests 2gp a day for a skilled hireling – so presumably a professional soldier falls under this; a mercenary certainly does. Therefore, this hypothetical soldier will be paid approximately 360gp for his campaign season work.
Alright, so not counting training costs, which are somewhat schizophrenic, the total deployment and upkeep cost for a single professional infantryman for 6 months is approximately 531.21gp. Now, that doesn’t sound like much – a single Level 4 character could hire a small squad of these men, with money left over.
But then think about the sort of army sizes that were fielded in the High Medieval period – at Crecy, England put together an army of 12,000; similarly, at Poitiers, the French army was about 13,000. So to estimate the cost for putting this sort of army in the field for a campaign season, is, say, 12,000 * 531.21 = 6,374,520gp. Now, this is actually lowballing the estimate significantly; it does not factor in the cost of mounted soldiers, ranged troops, siege engines, logistics experts or serious equipment upkeep. So the total, actual cost of a Medieval-esque army in DnD might be something more like 7 or 8 million gp for a 6 month campaign season. So, like I said, very expensive.
Reducing the Cost Well, any sensible nation would presumably be looking pretty closely into the potential to reduce costs; bankrupting your nation or levying very harsh taxes to pay for your military endeavours is probably not awfully desirable. Therefore, there are a couple of ways to help cut costs.
•Downgrade Equipment Quality: Whilst this is addressed more in the different unit type sections, one easy way to reduce cost is to reduce the quality of equipment. For example, a soldier with a longspear and leather armour can still fight effectively, and for about half the cost, of the scale armoured swordsman envisaged above. There are, of course, pros and cons to this move however.
•Reduce Pay, Increase Plunder: Whilst typically slashing pay is probably not a very good idea overall, the sting of losing pay can be mitigated, at least a little, by letting soldiers have rights to plunder the enemy, along with demand ransoms from the enemy. This does certainly manage to reduce some of the financial issues, but it brings with it a host of disciplinary issues, as soldiers might begin to prioritise getting their plunder ahead of actually fighting.
Foraging Foraging is a pretty important topic, so it demands its own section really. Foraging for an army of any appreciable size is not a matter of running into the bush and catching a brace of hares, or finding some edible berries. Whilst this can fulfil the needs of an adventuring party or other such small detachment, a major force would not be able to achieve all that much from living strictly off the land in such a fashion; it would swiftly degrade the local food sources such that it is impossible to remain foraging. Now, this can be countered a little by using detachments of cavalry and the like to gather food from off of the direct route of march, but that exposes elements to the enemy and slows down the provision of victuals to the men.
Foraging really, in this case, is a matter of acquiring food and goods from local populations near the line of march. Think less a group of woodsmen hunting deer, and more a company of cavalry intimidating the mayor of a local town into giving up his winter supplies. There are a number of permutations to this:
•Buying the food: Actually just purchasing required food from local villages at or even above market value (a favourite trick of Sulla’s) can go a long way to satisfying the logistical demands of an army, along with keeping the local population at the least neutral to the armies presence, if not amenable to it. However, it’d probably be cheaper just to buy rations.
•Letters of Receipt: Issuing receipts and promises to pay might work, but it is contingent on quite a few things. Firstly, it is not going to work if the operation is a raid or other such manoeuvre which does not involve taking the territory permanently, as otherwise the money would never reach the people there. Secondly, one needs to actually pay up, otherwise it will engender a deeply negative reputation.
•Just take it: Roll a company into a town, hold the mayor at sword-point, and demand he give you all of the food. Then, probably, torture him when the food does arrive to find where they’re hiding the rest of it. Take the food and ride off with it. A very morally dubious strategy, but one that does work, sort of. However, it would engender hate in the population against the army. Moreover, commoners can get pretty scary en masse, so there’s no guarantee it could work. Lastly, there is a non-zero possibility that the food provided is poisoned.
Therefore, I’d suggest against excessive foraging from the soldiers, if only because it opens up vulnerabilities in the ranks and impacts the campaign efficiency of the men. However, it would be a faint hope to assume that the soldiers in a pseudo-Medieval army could be truly professional, so I would imagine that much an army commander’s work would be making sure that the army does not cause too much damage to the local countryside.

Supply Train

As a note, most armies are going to have baggage trains and supply trains full of all manner of carts and vulnerable targets. Protecting these supplies is very much important, as their destruction could leave the army stranded in enemy territory without food or spare ammunition. Dedicating a contingent of casters and veteran troops to the rear-guard so as to keep the supply train safe would be a very prudent course of action.

Logistics Conclusion

Now, the study of logistics is incredibly important and very complicated – it is an old saying that “amateurs study tactics, professionals study logistics” and that is certainly true. This short piece could not hope to cover the field comprehensively, but I do hope it gives some sort of overview as to their importance and the sheer cost of maintaining an army in the field.