OD&D Combat: Initiative and the Combat Sequence

The first thing to work out when constructing a combat system for OD&D/CHAINMAIL is the combat sequence.  CHAINMAIL provides a perfectly adequate one, as shown below, but a few tweaks are required:

 

 

 

This is simple enough so far.  Both sides roll a die, and follow the steps given above.  If the die results are different, the Move/Countermove system is used.  If the results are the same, the Simultaneous Movement system is used.

A few things need to be added to the above sequence.   Dragon breath, and other breath weapons, I will place in the Artillery Fire phase.  Boulders thrown by giants will also go into that phase.  I'm placing spellcasting into its own phase, after Missile Fire but before Melee.  Spellcasters will start casting at the beginning of the round, and any damage taken before then will disrupt the spell.

The following rules from CHAINMAIL's Man-to-Man section will apply to determine who goes first in melee:

 

So on the first round of a melee the longer (higher-class) weapon strikes first, and on subsequent rounds the smaller and faster (lower-class) weapon strikes first.  The terms "attacker" and "defender" in the rules above are a bit vague, but I'm defining the attacker as the side that won initiative (regardless of whether they chose to move first or second).  Second round attacks won't be contingent on who attacked first in the previous round, but will still be determined by initiative roll (or weapon class, if applicable).  Of course, anyone fighting with natural weaponry won't have a weapon class, so the attack sequence will be entirely determined by initiative.

The final thing to incorporate into this system is this line from OD&D Vol. 1: "Dexterity applies to both manual speed and conjuration. It will indicate the character's missile ability and speed with actions such as firing first, getting off a spell, etc."  As I interpret the above combat sequence, the Artillery and Missile phases have both sides firing at the same time.  I would do the same for the Spellcasting phase.  The one thing I would change for each of these phases is to have characters with a high Dexterity (13-18) shoot or cast first, followed by those with average Dexterity (9-12), then those with low Dexterity (3-8).  Most monsters will have an average Dexterity rating, so this will most often advantage or disadvantage PCs, as the case may be.  To simplify things, Dexterity won't be a factor when using the Simultaneous Movement system.

When finalised, the Combat Sequence will look something like this:

COMBAT SEQUENCE

THE INITIATIVE ROLL

A die (1d6) is rolled to determine initiative at the beginning of each combat round.  Each side rolls, and the side with the highest score has the initiative.  The side with initiative chooses whether to act first (Move) or last (Counter-Move).  Proceed to the Move/Counter-Move System below.

 

If the rolls are equal, use the Simultaneous Movement System instead.

 

THE MOVE/COUNTER-MOVE SYSTEM

1. All characters on the side going first move
1. characters that are able to may split-move and fire
2. Stationary opponents may retaliate with pass-through fire
3. Melees resulting from a charge are resolved.
1. The side charging attacks first, unless:
1. the defender's weapon is 2+ classes higher
2. the defender is fighting from above (a castle wall, rampart, etc.)
3. Anyone is attacked from the rear or the left flank; characters attacked from the rear may not retaliate during the 1st melee round, and those attacked from the left flank must attack last
   
2. All characters on the side going last move
1. characters that are able to may split-move and fire
2. Stationary opponents may retaliate with pass-through fire
3. Melees resulting from a charge are resolved
1. The side charging attacks first, unless:
1. the defender's weapon is 2+ classes higher
2. the defender is fighting from above (a castle wall, rampart, etc.)
3. Anyone is attacked from the rear or the left flank; characters attacked from the rear may not retaliate during the 1st melee round, and those attacked from the left flank must attack last
3. Artillery missiles, Giant boulders, and breath weapons are fired, both sides firing simultaneously.
4. Missiles are fired, both sides firing simultaneously.  Characters with Dexterity of 13+ fire first, those with Dexterity 9-12 fire second, and those with Dexterity of 8 or lower fire last.  Unless otherwise noted, assume a Dexterity of 9-12.
5. Spells are cast, both sides casting simultaneously. Characters with Dexterity of 13+ cast first, those with Dexterity 9-12 cast second, and those with Dexterity of 8 or lower cast last.  Unless otherwise noted, assume a Dexterity of 9-12.
6. Melees are resolved. First blow in each round is determined as follows:
1. On the first round of a melee:
1. The side that has initiative strikes first unless
1. The defender's weapon is 2+ classes higher
2. The defender is fighting from above (a castle wall, rampart, etc.)
3. Anyone is attacked from the rear or the left flank; characters attacked from the rear may not retaliate during the 1st melee round, and those attacked from the left flank must attack last
2. On subsequent rounds:
1. The side which has initiative strikes first, unless
1. The opponent has a weapon 2+ classes lower
2. The opponent is fighting from above
3. Anyone was attacked from behind in the 1st round of melee; such characters always strike last on the next round
7. Roll for initiative again at the beginning of the next round.

 

THE SIMULTANEOUS MOVEMENT SYSTEM

1. Each player writes down what they want their character to do for the round, including direction of movement, and the referee does the same for the monsters
2. Every creature in the battle moves as per their written orders, making half of their move.
1. Opponents that come within 1" of each other have entered melee contact, and must stop moving.
2. All characters able to split-move and fire may do so, both sides firing simultaneously.
3. Stationary characters may make pass-through fire.
3. Every creature finishes the remainder of its ordered movement.
1. Melees resulting from a charge are resolved.
1. The side charging attacks first, unless:
1. the defender's weapon is 2+ classes higher
2. the defender is fighting from above (a castle wall, rampart, etc.)
3. Anyone is attacked from the rear or the left flank; characters attacked from the rear may not retaliate during the 1st melee round, and those attacked from the left flank must attack last
4. Artillery missiles, Giant boulders, and breath weapons are fired, both sides firing simultaneously.
5. Missiles are fired, both sides firing simultaneously.
6. Spells are cast, both sides casting simultaneously.
7. Melees are resolved.
1. On the first round of a melee:
1. Both sides strike simultaneously unless
1. One opponent's weapon is 2+ classes higher
2. One opponent is fighting from above (a castle wall, rampart, etc.)
3. Anyone is attacked from the rear or the left flank; characters attacked from the rear may not retaliate during the 1st melee round, and those attacked from the left flank must attack last
2. On subsequent rounds:
1. Both sides strike simultaneously, unless
1. One opponent has a weapon 2+ classes lower
2. One opponent is fighting from above
3. Anyone was attacked from behind in the 1st round of melee; such characters always strike last on the next round
8. Roll for initiative again at the beginning of the next round.

 

Split-move fire and pass-through fire (see the Missile Fire section of this chapter) take effect immediately during the movement phase.  All other artillery and missile fire occurs simultaneously just prior to melee.

 

It is not shown here when morale checks should be made.  They can occur during any kind of missile fire, as well as after melee, and must be made whenever the rules require. See Morale for more details.

 

"Charge-if-Charged"

This special charging rule can only be performed by cavalry. It can only be done during a Simultaneous Movement turn sequence. It must be declared as part of a character's written orders before the round begins.

 

The character ordered to "Charge-if-Charged" may react to any charge made by an enemy creature (provided the charge is at the character or an ally of that character).  This enemy creature must be within the character's charging range when its charge begins.  The character charges that creature, beginning at the second phase of movement and charging up to one-half of a normal charge move.

 

All other charging rules and bonuses apply.