"Two moves constitute a turn" (U&WA p8), and furthermore let's assume there are two moves per combat turn (more on this in a later post).
D. Without surprise, and with two move per turn.
The players have time for two volleys of missiles before melee contact occurs.
While movement rate is central to the following discussion of moves per turn, it is important to note that Giant Spiders did not have published statistics until the AD&D Monster Manual (December 1977)–these later appeared in the 2nd print of Holmes (November 1978).
While both CHAINMAIL and the 3LBBS state explicitly that there is a movement bonus when charging into melee, Holmes does not mention this detail explicitly. There is a possibility (albeit a remote one) that Holmes may have assigned his Giant Spiders a base movement rate of 3″, to which he added a 2″ charge bonus in order to achieve the movement rate of 5″ given in the example. Other explanations may be more probable.
For the sake of the following comparison, I will assume that the published 5″ movement rate is inclusive of any charge bonus.
A party of adventurers is standing at an intersection of corridors when the Dungeon Master rolls a "wandering monster." Using the Wandering Monster Table, he determines that the party has encountered six giant spiders with 1 hit die each and they are 100 feet away.
​[DECLARATION]​ ​The players use their surprise as a missile/magic segment in which ​"Flubbit" the magic-user throw​s​ a sleep spell, and the fighters ​​fire arrows​.
​[SURPRISE SEGMENT] ​The Dungeon Master rules that only the two fighters in the front row and Flubbit have a clear field of fire. The two fighters agree to both shoot at "the one on the left". They throw a 3 and an 18. The spiders are armor class 3 (plate), and the range is medium for the longbow (100 ft), so the 18 is a hit and is found to do 4 damage points. The spider's hit die is rolled and comes up a 4—the creature is killed by a lucky arrow hit!
Flubbit's sleep spell affects another four of them.
[​​​1ST TURN; ​MOVEMENT SEGMENT] The last spider comes at them fast, covering 50ft in its move (assuming a 3″ move + 2″ charge bonus).
[​​​1ST TURN; MISSILE​/MAGIC​ SEGMENT] the Dungeon Master rules that only the two fighters in the front row have a clear field of fire. As stationary longbow men not meleed at the end of the move segment, they get off two arrows apiece when the last spider is 50 feet away.
For their second volley they throw an 8 and a 12 so their shafts bounce off the monster's armor again.
Flubbit is not meleed at the end of the spiders' movement segment so could throw another spell, but he decides not to waste his magic on a single spider.
[​2ND TURN; ​MOVEMENT SEG.​; FIRST HALF MOVE​] The last spider keeps coming… At the halfway point of its 5″ move the spider will have covered 25ft of the remaining 50ft gap–and will still be 25ft away.
[​2ND TURN; ​MOVEMENT SEG.​; PASS THRU FIRE] The gap between the spider and the fighters is now 25ft, which falls right between two important markers; 1″ and 3″.
* CM explains that man-sized figures control the space within 1″ around them; they can decide to attack other figures within that distance, and so 1″ is considered to be "melee contact".
* CM and U&WA also refer to 3″ as "melee range" and "the range indicated (sic) for melee". CM explains this as the distance a figure can cover to join an existing melee.
Technically, there is no preexisting melee in this scenario, so the two archers cannot move across 3″ to join combat. Moreover, their intent was to fire missiles not advance into combat. Therefore, the fighters would instead take the opportunity to give another round (their fourth!) of pass through fire with their longbows.
[​2ND TURN; ​MOVEMENT SEG.​; SECOND HALF MOVE​] The last spider is upon them, biting! The last spider covers the final 25ft to reach the fighters. In fact, it only needed to cover 15ft to achieve melee contact at 1″. The fighters and the spider are now considered to be "meleed".
​[2ND TURN; MELEE SEGMENT] The two fighters drop their bows and draw swords for melee, missing the first round as they change weapons, while the spiders have the benefit of the impetus bonus in the first round.
* Three (potentially even four!) opportunities to fire missiles.
​[SURPRISE CHECK] T​here is no surprise.
[​​​1ST TURN; ​MOVEMENT SEGMENT; 1ST HALF MOVE] The spiders come at them fast, covering 25ft in their first half move (assuming a 3″ move + 2″ charge bonus).
[​​​1ST TURN; ​MOVEMENT SEGMENT; 2ND HALF MOVE] The remaining five spiders cover another 25ft, closing the gap to 50ft.
[​​​1ST TURN; MISSILE​/MAGIC​ SEGMENT]As stationary longbow men who are not meleed at the end of the move segment are allowed two shots per turn, the two fighters get off another arrow apiece when the spiders are 50 feet away, this time adjusted by +1 at short range. They throw an 8 and a 12 so their shafts bounce off the monsters' armor.
Now Flubbit's sleep spell goes off, but it only affects four of them.
​[​2ND TURN; ​MOVEMENT SEG.​; FIRST HALF MOVE​] The last spider keeps coming… At the halfway point of its 5″ move the spider will have covered 25ft of the remaining 50ft gap–and will still be 25ft away.
[​2ND TURN; ​MOVEMENT SEG.​; PASS THOU FIRE] See remarks in case A. above. Technically, the two fighters have an opportunity to give pass through fire again, which would be their third missile volley.
​[2ND TURN; MELEE SEGMENT] The two fighters drop their bows and draw swords for melee,missing the first round as they change from bows to swords, while the spiders have the benefit of the impetus bonus in their first round.
* Movement first, then missiles, then spell.
* Three opportunities to fire missiles.
​[SURPRISE SEGMENT] ​The Dungeon Master rules that only the two fighters in the front row and Flubbit have a clear field of fire.
The two fighters agree to both shoot at "the one on the left". They throw a 3 and an 18. The spiders are armor class 3 (plate), and the range is medium for the longbow (100 FT), so the 18 is a hit and is found to do 4 damage points. The spider's hit die is rolled and comes up a 4—the creature is killed by a lucky arrow hit!
​[MOVEMENT SEGMENT; 1ST MOVE] ​The last spider comes at them fast, covering 50ft (assuming a 3″ move + 2″ charge bonus).
​[MOVEMENT SEGMENT; PASS THRU FIRE] The archers get off one arrow apiece as the spider is 50 feet away; they throw an 8 and a 12 so their shafts bounce off the monster's armor.
​[MELEE SEGMENT] AS the two fighters drop their bows and draw swords for melee​, ​missing the first round as they change from bows to swords, while the spiders having the benefit of the impetus bonus in their first round.
* Exactly two opportunities to fire missiles.
​[SURPRISE CHECK] ​there is no surprise.
​[MOVEMENT SEGMENT; 1ST MOVE] The spiders combat at them fast, covering 50ft (assuming a 3″ move + 2″ charge bonus).
[MOVEMENT SEGMENT; PASS THRU FIRE] ​The Dungeon Master rules that only the two fighters in the front row have a clear field of fire, and they get off one arrow apiece ​when​ the spiders are 50 feet away. The two fighters agree to both shoot at "the one on the left". They throw a 3 and an 15. The spiders are armor class 3 (plate), and the range is short for the longbow (50 FT), so the 15 is a hit and is found to do 4 damage points. The spider's hit die is rolled and comes up a 4—the creature is killed by a lucky arrow hit!
​[MISSILE/MAGIC SEGMENT] The two fighters are meleed, so they cannot fire. However–assuming he is sensibly positioned at least 3″ behind the fighters–Flubbit is not meleed so his sleep spell goes off. The sleep spell is an area effect, so the referee dices to determine which four among the five spiders and two fighters are affected; luckily Flubbit's sleep spell affects four spiders and none of his allies.
[MELEE SEGMENT] The two fighters drop their bows and draw swords for melee, ​missing the first round as they change from bows to swords, while the spiders have the benefit of the impetus bonus in their first round.
* Exactly one opportunity to throw spells.
Only one of the four combinations explored enables the players to throw a spell first, and to fire exactly two volleys of missiles before melee contact. That combination is: with surprise and with two moves per turn.
While it's unlikely that Holmes stuck to the simultaneous movement system in the detail explored above (in fact, he discusses movement per round rather than per turn), it seems plausible that we can get the same result as Holmes with the original turn structure–assuming a surprise segment and two moves per turn.
There are relatively few clues given in the 3LBBs about the structure of original D&D's combat turn, and what other clues exist are scattered through early D&D artifacts that are mostly pretty hard to come by. However, the "Second Combat Example" appearing in Holmes is one of the more detailed (and readily accessible!) accounts of the original D&D combat turn that we have in print today.
Two years ago we determined to revise the whole of D&D in order to clean up the errors and fill in the holes. The project is a long and complicated one, a task not accomplished overnight.
Regardless of its precise inception date, it is clear that Holmes was devised during original D&D's hey-day, and that it is a neat representation of an important part of those rules. It is, perhaps, the first original D&D clone in today's sense of the term—counter edited by EGG to boot.
A party of adventurers is standing at an intersection of corridors when the Dungeon Master rolls a "wandering monster." Using the Wandering Monster Table, he determines that the party is being attacked by six giant spiders with 1 hit die each and they are 100 feet away. "Flubbit" the magic-user throws a sleep spell but it only affects four of them, the other two keep coming. The party decides to fire arrows, the Dungeon Master rules that only those in the front row have a clear field of fire. The spiders are 50 feet away and coming fast. Two characters get off arrows from their long bows and they agree to both shoot at "the one on the left." They roll a 3 (an obvious miss) and a 15. The spiders are armor class: 3 (plate), but the range is medium for the longbow, the 15 is a hit and is found to do 4 damage points. The spider's hit die is rolled and comes up a 4–the creature is killed by a lucky arrow hit! The second spider keeps coming. The archers get off one more arrow apiece, an 8 and a 12, and the shafts bounce off the beast's armor. The two fighters drop their bows and draw swords as the monster is upon them, biting!
A party of adventurers is standing at an intersection of corridors when the Dungeon Master rolls a "wandering monster." Using the Wandering Monster Table, he determines that the party is being attacked by six giant spiders with 1 hit die each and they are 100 feet away.
Firstly, player light sources typically have a 30ft radius, but since visibility is not otherwise mentioned in the example we might presume the area is lit.
Secondly, unlike OD&D Holmes has random encounters occurring at 20–120ft distance regardless of whether surprise occurs. This is an important nuance, below.
"Flubbit" the magic-user throws a sleep spell but it only affects four of them, the other two keep coming.
It is significant that the player spell is the very first action of the combat turn. For this to be the case, the players must have won a surprise segment and employed it as a missile/magic segment. Without surprise, we would have expected to see the example go immediately to the first movement segment, but we did not.
Note, however, that the unaffected spiders "keep coming". That they "keep" coming implies they were already on the move as Flubbit threw his spell, which is at odds with the notion of a surprise segment.
Significantly, they didn't require a morale check after two-thirds of them were magicked (presumably due to their limited intelligence).
The party decides to fire arrows, the Dungeon Master rules that only those in the front row have a clear field of fire. The spiders are 50 feet away and coming fast.
Importantly, the spiders have already closed to 50ft before the players loose their arrows. This must be the result of their first move (of two possible moves) during their movement segment. The movement segment is formally the first segment of each combat turn, so this is presumably demarks the beginning of the first regular combat turn.
It is also curious the spiders cover 50ft. Holmes gives the 1 HD variety of fantastic spiders a movement stat of "60ft per turn". This most likely implies a 6″ movement rate in OD&D terms, so it may have been better stated as "60ft per move". None the less, 50ft is within the spiders' possible movement distance of 60ft.
Two characters get off arrows from their long bows and they agree to both shoot at "the one on the left." They roll a 3 (an obvious miss) and a 15. The spiders are armor class: 3 (plate), but the range is medium for the longbow, the 15 is a hit and is found to do 4 damage points. The spider's hit die is rolled and comes up a 4—the creature is killed by a lucky arrow hit! The second spider keeps coming.
Now our two fighters fire their first round of arrows, after the spiders have already covered 50ft of ground.
Note that 50ft range is erroneously said to be medium range for longbows. In fact, the target would have to be at least 70ft away to qualify as medium range for a longbow. This is important because–according to the Holmes attack matrix–a 1st level fighter requires a throw of 16 to hit AC 3 (plate), with short range adjusting the throw by +1. Thus, a throw of 15 would be a miss at medium range, but a hit at short range.
This round of missile fire could possibly represent pass through fire during the spiders' movement segment, but because the subsequent round of missile fire (see below) must necessarily be pass through fire, this first round of missile fire can only have occurred during the surprise segment, before the spiders' fist move. It should therefore have occurred at 100ft range–which would have correctly been at medium range, as stated in the example.
The second spider keeps coming.
This must be the spider's second move (of two possible moves) during its movement segment. This movement results in melee contact (see below) because the spider covers the remaining 50ft of ground to contact the players.
It is worth noting that melee contact occurs at 1″ range (for man-sized figures), so the spider needed to cover only 40ft in its second move to achieve melee contact. Additionally, CM and OD&D allow most man-like figures a 3″ bonus to their movement speed when charging into contact. This detail is ignored in the Holmes example.
The archers get off one more arrow apiece, an 8 and a 12, and the shafts bounce off the beast's armor.
This second round of missile fire from the players is potentially problematic because the spider's second move results in melee contact.
According to CM (and hence OD&D) melee contact disallows any further missile fire. Therefore, this second round of missile fire can only legally have occurred as pass through fire during the spiders' movement segment—between their first and second moves. For this to be the case, the first round of missile fire (above) must have occurred during the surprise segment, before the spiders' first move.
The two fighters drop their bows and draw swords as the monster is upon them, biting!
Now that melee contact has occurred, and we enter the melee segment. Our front-most pair of fighters now drop their bows to change to melee weapons, losing the opportunity to attack in the first round.
If there were a second rank of fighters ready, and sufficient room behind them, our front-most missile-men technically could have refused combat and withdrawn behind them. However, that is not the subject of this post.
Despite there being a few question marks around surprise and the precise sequence of missile fire, Holmes' famous combat example is generally explainable in terms of CM's Simultaneous Movement System in the context of D&D. Importantly, it is possible for the magic-user to throw his spell first (with surprise), and for the archers to fire two volleys before melee contact occurs.