In Dungeons and Dragons, wizardly evocations are normally considered to dominate the battlefield. But is that true? Is it possible to have magic and still field traditional units of hundreds or thousands of men?
Considered a unit of 100 men, in a 50 x 50 ft square. Since they are common soldiers, with 1d4 hit die and no bonuses, we can assume they fail all saves and any damage kills them.
A Fireball has a 20 ft spread. This means it affects a maximum of 52 five-foot cubes. However, fireballs are emanations; they can be blocked by cover. The four soldiers adjacent to the center of the blast have no cover; but the 8 soldiers around them have the bodies of their comrades as Half cover (so a +2 to their save). The men beyond that have at least 2 bodies providing cover, so that counts as Nine-Tenths cover (+3 to their save). All of the rest of the men in the unit have at least 3 bodies between them and the blast, so unless the damage is sufficient to incinerate the corpses (which would require at least five times CON, I would think), they are safe. This means only 24 men will die: only a quarter of the unit.
Suppose the wizard gets clever, and aims the fireball so it is 10 ft off the ground. This air burst denies cover to the men underneath; but it also expends its maximum radius harmlessly in the air. The ideal balance between area of effect and cover comes to the same thing: 24 casualties.
Obviously that is a lot. But a 5th level wizard can only cast 1-3 Fireballs a day; that means that a 100 man pike unit is roughly equivalent to a 5th level wizard on the battlefield. If the wizard is good or lucky, many men will die and the rest will flee; if the men are dedicated and brave, the wizard will run out of spells and then die on their pikes. (Of course smart wizards would cast Fly... but then we would be talking about 100 crossbowmen. And that would be one less Fireball they can cast). Interestingly, higher level fireballs are no more effective, since their radius does not increase.
In a low magic world, with armies numbering in the thousands and only a handful of wizards, this means magic is a powerful force on the battlefield, but not the only force.
Lightning bolts are less effective; although they specifically deal damage to everything in their area, they have a small area of affect. They will only kill 10 men out of the unit (and 10 men out of the next unit, if they are adjacent).
10 foot radii spells like Flame Strike, Freezing Sphere, and Sound Burst are small enough that cover does not matter; but they only slay 12 men.
Higher-level spells that have 20 ft radii and do not allow cover will kill all 52 affected men in a single blast: Ice Storm, Black Tentacles, Unholy Blight, Cloudkill, Song of Discord, Acid Fog, Incendiary Cloud. Effects that can move will likely destroy the entire unit (unless the survivors flee). A Wall of Fire cast in its smallest circular form and facing inward will kill 52 men; facing outward, it will kill 72 men and trap the remaining 28 inside to be dealt with later. In its linear form it will kill the first 2 rows of men along its line of effect (so 20 men from one unit); the rest will have sufficient cover to retreat before the lower-level damage affects them.
The 40 foot radius spells are all centered on the caster: Holy Word, Blasphemy, Dictum, Word of Chaos. These affect 74 men if the caster is in the center of the front line.
A 50 foot radius Bless will affect 2 units.
Spells that create 10 ft cubes will kill 4 men per cube (Summon Swarm, Call Lightning, Spike Growth, Order's Wrath, Spike Stones, Call Lightning Storm, Insect Plague, Wall of Thorns, Fire Seeds, Firestorm, Creeping Doom, Prismatic Wall). These spells kill between 4 and 120 men; those that persist and move quickly will kill more; those that move slowly can be used to shape the battlefield. Reverse Gravity needs to be doubled up to inflict serious damage, so it will only kill 14 ordinary men: hardly worth a 7th level slot.
Cones are better, but require getting close to your target. 15 foot cones like Burning Hands only kill 7 men in an optimal casting; 30 foot cones like Shout and Wave of Fatigue can kill 24 men; 60 foot cones such as Cone of Cold, Greater Shout, Wave of Exhaustion and Prismatic Spray can kill 75 men, assuming they are not blocked by cover. With cover, 30 foot cones only slay 17 men and 60 foot cones only kill 30.
Symbols of Death, Insanity, and so on affect an entire adjacent unit (although the symbol of Death only does 150 hit points before burning out). After that no one will be silly enough to get close to them.
Earthquake affects an 80 foot radius, which might well be 4 entire units if they are adjacent; but it only inflicts 25% casualties. After the ground stops shaking, the troops will count themselves lucky not to have been fireballed.
Meteor Swarm creates 40 foot radius blasts, but these will be blocked by cover, so only 24 men per blast will be affected. The dreaded Storm of Vengeance will kill everything within its 360 ft radius (i.e. 150 fifty-foot battle squares!) but only after the 4th round. This basically means that summoning the storm causes the enemy army to immediately break ranks and flee for their lives (unless they are protected by sufficient fortifications such as a castle or keep).
Summoned monsters, of course, will also be effective; but soldiers are trained to fight monsters. 100 well-ordered pikemen can send a fistful of Dire Wolves packing.
In addition, the use of Tower Shields, or Large Shields and testudo formations can grant Total cover against spells and arrows. A Large Steel Shield, with its Hardness of 10 and Hit Points of 20, could even withstand a Meteor Swarm!
Thus, with careful review of the effects of spells, and appropriate strategic planning (no use letting the wizard fly away to fireball you again the next day), I think the strength of ordinary men and common steel can still decide the fates of kingdoms. Against an 11th level wizard, a thousand men backed up by only a handful of mid-level clerics and armed with a way to trap the wizard into fighting (for example, attacking his home town), may yet see victory.
What do you all think?
(Yes, I just watched The Return of the King again. Why do you ask? :smallbiggrin:)