Tag Archives: ironclads

The Tangled Origins of D&D’s Armor Class, Hit Points, and Twenty-Sided Die Rolls To-Hit

In 1977, when I first read the Dungeon & Dragons basic rules, the way armor class improved as it shrunk from 9 to 2 puzzled me. Shouldn’t higher numbers be better? Players just used AC to find a row on a table, so rising ACs would have worked as well. Magic armor introduced negative ACs, making the descending numbers even more awkward. Also, many of the demons described in 1976 in the Eldrich Wizardry supplement sported negative armor class.

D&D’s designers seemed to think rising armor classes made more sense. The game rules stemmed from co-creator Gary Gygax’s Chainmail rules for miniature-figure battles. Chainmail rated armor from 1 to 8, with better armor gaining higher values. Co-creator Dave Arneson based his Blackmoor fantasy campaign on Chainmail. His campaign developed into D&D. In Blackmoor, higher armor classes represented better armor.

So how did the first D&D rules set the puzzling convention of descending armor class?

The answer lies toward the end of the genesis of D&D’s combat system.

In the original D&D rule books, the combat system that everyone used appears as the Alternative Combat System. “Alternative” because players could just use the combat system from Chainmail instead. When Dave launched Blackmoor, he tried the Chainmail system. But it focused on battles between armies sprinkled with legendary heroes and monsters. For ongoing adventures in the dungeon under Castle Blackmoor, the rules needed changes. Original Blackmoor player Greg Svenson recalls that within about a month of play, the campaign created new rules for damage rolls and hit points. (More recently, Steve Winter, a D&D designer since 1st edition, tells of playing the original game with the Chainmail combat rules.)

Much of what we know about how Dave adapted the rules for his Blackmoor campaign comes from two sources: a 2004 interview and The First Fantasy Campaign, a raw publication of notes for his game. Most quotes in this post come from those sources.

Chainmail’s melee combat matrix

To resolve melee combat, Chainmail used a combat matrix. Players matched the attacking weapon or creature against the defender, rolled a pair of 6-sided dice, and consulted the table for an outcome. “That was okay for a few different kinds of units, but by the second weekend we already had 20 or 30 different monsters, and the matrix was starting to fill up the loft.”

Dave abandoned the matrix and extended Chainmail’s rules for missile attacks to melee combat. In Chainmail, ranged attackers rolled 2d6, and tried to roll higher than a target number based on increasing armor classes. Blackmoor gained melee to-hit rolls.

Chainmail’s man-to-man combat and ranged combat tables

In Chainmail, creatures lacked hit points, so a single hit killed. But with extraordinary individuals like heroes, wizards, and dragons, a saving throw allowed a last chance to survive. For example, the rules say, “Dragon fire will kill any opponent it touches, except another Dragon, Super Hero, or a Wizard, who is saved on a two dice roll of 7 or better.”

Under rules where one hit destroyed a character, Dave tried to spare player characters by granting saving throws against any hit. “Thus, although [a character] might be ‘Hit’ several times during a melee round, in actuality, he might not take any damage at all.”

But the system of saving throws still made characters too fragile to suit players. “It didn’t take too long for players to get attached to their characters, and they wanted something detailed which Chainmail didn’t have,” Dave explains.

Chainmail battle on a sand table

“I adopted the rules I’d done earlier for a Civil War game called Ironclads that had hit points and armor class. It meant that players had a chance to live longer.” In a Chainmail battle that featured armies spanning a sand table, hit points would have overwhelmed players with bookkeeping. But the Blackmoor players liked the rule. “They didn’t care that they had hit points to keep track of because they were just keeping track of little detailed records for their character and not trying to do it for an entire army. They didn’t care if they could kill a monster in one blow, but they didn’t want the monster to kill them in one blow.”

When players rolled characters, they determined hit points. For monsters, hit points were set based “on the size of the creature physically and, again, on some regard for its mythical properties.” Dave liked to vary hit points among individual monsters. To set the strength of a type of monster while rolling for an individual’s hit points, he probably invented hit dice.

Dave said he took the armor class from Ironclads, but the concept came from Chainmail and the term came from its 1972 revisions. I suspect Dave meant that he pulled the notion of hit points and damage from a naval game that featured both armor ratings and damage points. Game historian Jon Peterson explains, “The concepts of armor thickness and withstanding points of damage existed in several naval wargames prior to Chainmail.” Still, nobody has found the precise naval rules that inspired Dave. Even his handwritten rules for ironclad battles lack properties resembling armor class. Perhaps he just considered using the concept in a naval game before bringing the notion to D&D.

In Blackmoor, Dave sometimes used hit locations. Perhaps naval combat inspired that rule. When ships battle, shells that penetrate to a boiler or powder keg disable more than a cannonball through the galley. Likewise, in man-to-man combat, a blow to the head probably kills.

Dave’s rules for hit locations only reached D&D in the Blackmoor supplement, which came a year after the game’s release. But hit locations made combat more complicated and dangerous. Realistic combat proved too deadly for the dungeon raids in D&D. So D&D players never embraced hit locations. Even Dave seemed to save the rule for special occasions. “Hit Location was generally used only for the bigger critters, and only on a man-to-man level were all the options thrown in. This allowed play to progress quickly even if the poor monsters suffered more from it.” Dave ran a fluid game, adapting the rules to suit the situation.

By the time Dave’s fantasy game established hit points, 2d6 to-hit rolls, and damage rolls, he showed the game to Gary Gygax.

Next: Gary Gygax improves hit points by making them more unrealistic, and then adds funny dice

The brilliance of unrealistic hit points

(This post continues a discussion I started in “What does D&D have to do with ironclad ships?”)

After the role-playing game hobby’s first 10 years, designers turned from strict realism and began to design rules that both supported a game’s flavor and encouraged its core activities. Runequest‘s realistically lethal combat systemParanoia 1st edition game fit the fearful world of Call of Cthulhu (1981), as did a new sanity system. Paranoia (1984) built in rules that encouraged a core activity of treachery, while giving each character enough clones to avoid hard feelings.

Today, this innovation carries through stronger then ever. Dungeons and Dragons’ fourth-edition designers saw D&D’s fun in dynamic battles and showing off your character’s flashy capabilities, so they optimized rules that heightened that aspect of the game, possibly to the expense of other aspects.

When Dave Arneson mashed rules for ironclads into Chainmail, he probably gave little thought to supporting the D&D play style that would launch a hobby, but he created some brilliant conventions.

Chainmail gameThe best idea was to give characters steadily increasing hit point totals that “reflect both the actual physical ability of the character to withstand damage─as indicated by constitution bonuses─and a commensurate increase in such areas as skill in combat and similar life-or-death situations, the ‘sixth sense’ which warns the individual of otherwise unforeseen events, sheer luck and the fantastic provisions of magical protections and/or divine protection.” (Gary wrote this rationale for hit points in the first edition Dungeon Master’s Guide.)

Every “realistic” system to follow D&D used hit points to measure a character’s body’s physical capacity to survive injury. In D&D, rising hit points work as an elegant damage-reduction mechanic. Using hit points for damage reduction boasts a number of virtues:

  • Combat plays fast because players do not have to calculate reduced damage for every single hit.
  • Although damage is effectively reduced, the reduction never makes a combatant impervious to damage.
  • Once characters gain enough points to survive a few blows, hit points provide a predictable way to see the course of battle. If a fight begins to go badly, the players can see their peril and bring more resources like spells and potions to the fight, or they can run. In a realistic fight, things can go bad in an instant, with a single misstep resulting in death.
  • Most attacks can hit and inflict damage, providing constant, positive feedback to players while everyone contributes to the fight. Realistic combatants do not wear down from dozens of damaging blows; instead each hit is likely to kill or maim. In more realistic systems like Runequest and GURPS, when two very skilled combatants face off, they block or dodge virtually all attacks. The duels turn static until someone muffs a defense roll and lets a killing blow slip through. This model may be realistic─it reminds me of those Olympic competitions where years of training turn on a single, split-second misstep─but the realistic model lacks fun. No popular sports begin as sudden-death competitions where the first to score wins.
  • Battles can gain a dramatic arc. Fights climax with bloodied and battle-worn combatants striving to put their remaining strength into a killing blow. No one likes to see the climactic battle fizzle with a handful of bad rolls, especially at their character’s expense.

Bottom line: Using hit points for damage reduction enables a combat system where you can hit a lot, and hitting is fun.

Critics of inflated hit points still had a point. Using hit points as a damage-reduction mechanic can strain credulity, especially when you cannot explain how a character could reasonably reduce the damage he takes. Why should an unconscious or falling hero be so much more durable than a first-level mook?  Why does cure light wounds completely heal the shopkeeper and barely help a legendary hero? Over the years, we’ve seen attempts to patch these problems. For example, I liked how fourth edition’s healing surge value made healing proportional to hit points, so I’m sorry to see D&D Next turn back to the traditional hierarchy of cure spells.

D&D maintains a deliberate vagueness about the injuries inflicted by a hit. This abstraction makes possible D&D’s brilliant use of hit points as a damage-reduction mechanic. Fourth edition exploits the ambiguity more than ever, making plausible the second wind and the healing power of a warlord’s inspiration. 4E explicitly makes hit points as much a measure of resolve as of skill, luck and physical endurance. Damage apparently exists as enough of an abstraction that even if a hit deals damage, it doesn’t necessarily draw blood.

Even as 4E aims for the loosest possible interpretation of a hit, it makes the hit roll more important than in any prior edition. In 4E, melee hits can inflict crippling effects without saves. Just getting hit automatically subjects you to poison, or paralysis, or whatever. In past editions, if the spider bit or the ghoul clawed, you took the damage, but you still got an immediate save.

In the early days of the RPG hobby, many games attempted to fuse D&D’s fantastic setting with a more realistic model of combat damage. Although a few of these games enjoyed success, none recreated the combat-intensive, dungeon-bashing play style pioneered by D&D. At the time, no one seemed to realize that the clever damage-reduction mechanism built into game enabled the game’s play style.

Video game designers figured it out. Virtually every video game that combines fighting with character improvement features D&D-style rising hit points.

Next: Hitting the to-hit sweet spot

What does D&D have to do with ironclad ships?

Dave ArnesonWhen Dave Arneson set out to create the combat system that would become a pillar of Dungeons & Dragons, he did not aim to create a realistic simulation.  In a 2004 interview, he describes the system’s genesis from Gary Gygax’s Chainmail rules.

Combat in Chainmail is simply rolling two six-sided dice, and you either defeated the monster and killed it…or it killed you. It didn’t take too long for players to get attached to their characters, and they wanted something detailed which Chainmail didn’t have. The initial Chainmail rules was a matrix. That was okay for a few different kinds of units, but by the second weekend we already had 20 or 30 different monsters, and the matrix was starting to fill up the loft.

I adopted the rules I’d done earlier for a Civil War game called Ironclads that had hit points and armor class. It meant that players had a chance to live longer and do more. They didn’t care that they had hit points to keep track of because they were just keeping track of little detailed records for their character and not trying to do it for an entire army. They didn’t care if they could kill a monster in one blow, but they didn’t want the monster to kill them in one blow.

So the D&D rules for hit points and armor class stem from rules for ironclad ships trading cannon blasts, hardly the basis for an accurate simulation of hand-to-hand battles.

Soon after I began playing D&D, the unrealistic combat rules began to gnaw at me. In the real world, armor reduces the damage from blows rather than making you harder to hit. Shouldn’t it work the same way in the game? And how could a fighter, no matter how heroic, survive a dozen arrow hits, each dealing enough damage to kill an ordinary man? In reality, a skilled fighter would stand a better chance of evading blows, but no better chance of surviving a single hit.

Quest for realism

In the decade after D&D’s introduction, a mania for creating realistic alternatives to D&D dominated the hobby. Every D&D player who ever wielded a sword in the Society of Creative Anachronism cooked up a more realistic alternative to the D&D combat system. Runequest (1978) stands as the greatest early success. Characters’ hit points remained constant, but they became more able to dodge and block blows. Hit locations transformed characters from blobs of hit points into flesh and bone. Armor reduced damage by deflecting and cushioning blows. Arms Law and Claw Law

If you enjoyed the AD&D Weapon Armor Class Adjustment table, but felt it needed to go much, much further, the Rolemaster Arm’s Law (1980) system offered more than 30 tables matching weapons versus armor.

In this era, everyone formulated a critical hit table, because nothing adds fun to a system like skewered eyes, fountaining stumps, and sucking chest wounds. (Follow this blog for my upcoming list of supposedly fun, but not fun, things we did in the early days of role playing.)

I sought realism as much as anyone, first with Runequest, and then with GURPS. I quickly learned that making combat more realistically deadly made D&D-style, combat-intensive play impractical. Forget dungeon crawls; even skilled characters would eventually perish to a lucky blow. As I described in Melee, Wizard, and learning to love the battle map, early D&D combat lacked excitement anyway, so I hardly missed all the fights.

But I would come to realize that my dismissal of the D&D combat system was completely wrong.

Next: The brilliance of unrealistic hit points