As a generic answer for the non-hardcore fan, I think most people would define the following:
- OD&D (aka D&D 0e) including the original Brown Box and White Box versions from 1974.
- Classic (BECMI) D&D (including everything from BD&D in 1977 through the Rules Cyclopedia of 1991 and the Classic D&D Game starter set)
- AD&D 1st Edition (core books released 1977-1979)
- AD&D 2nd Edition (released 1989)
- D&D 3rd Edition (2000)
- D&D 3.5 Edition (revision of 3rd edition, released 2003)
- D&D 4th Edition (2008, including D&D Essentials, as D&D 4th edition has been erratad to the point that Essentials is at now)
- D&D 5th Edition (2014, aka D&D Next)
Certainly you could split it further (the various Mentzer/Moldvay differences, etc.) , but those are the major divides most gamers would likely note.
Of course, no edition of D&D survives contact with a gaming group intact; if there are 40,000 D&D sessions this weekend, there will be just about as many “versions” being played.
This is addressed directly in Mordenkainen's Tome of Foes
The first chapter is all about the Blood War. A very simplified and brief synopsis of the reasons the Blood War is a stalemate:
- Demons have quantity
- Devils have quality
- There are groups and individuals acting as intentionally balancing forces who are sufficiently powerful to manage any side that might get the upper hand.
The Balance
On page 8, there is a description of the sorts of players who intentionally keep the balance where it is in the Blood War.
... A third point of view exists, held by those who take both sides at their word and strive to make sure that neither outcome ever comes to pass.
The adherents of this viewpoint ... seek to maintain equilibrium across the cosmos above all. Mordenkainen and his compatriots are among its most notable devotees... Those few, however, make up a formidable force that can mix martial and magical power to keep the extremists of the Blood War in check.
General Statemate Summarized: Progress for both sides has difficulty
Demons have difficulty controlling a horde
(MtoF p.7)
More important, demons that are slain and sent back to the Abyss return to their chaotic wanderings in that realm. A demon lord is thus hard pressed to keep a horde cohesive as it takes casualties.
Devils have their own material concerns
(MtoF p.7)
If the devils extended a tenacious defense out to the planes beyond Avernus, they could keep the demons away from Hell's doorstep, but such a strategy would place a great strain on supplies, reinforcements, and unit integrity. Although the devils killed in such places would recover, their weapons, armor, and other materials would remain lost.
Minor points about permadeath
Lemures
The foot soldiers on the devil's side don't suffer permadeath in the same way devils and lesser devils do. (MToF p. 7, 17)
Hordes of lemures, devils that are permanently destroyed only if subjected to holy energies, are used to blunt demonic incursions.
Devils may care
The prospect of being destroyed permanently is not seen as a detriment to the devils. (MToF p. 7)
Also, the prospect of a permanent death compels the devils fighting on Avernus to maintain the utmost readiness and coordination. Wounded devils
retreat, knowing that fresh reinforcements can continue the fight.
Mercenaries
There are a class of fiends that don't get destroyed in either of the major arenas of the Blood War, and thus are a constant source of martial power for both sides. (MToF p. 8)
Yugoloths are major players on both sides of the Blood War. The death of a yugoloth is meaningless when it occurs in the Abyss or the Nine Hells, and thus these mercenaries freely give their all in any battle even when it means fighting other yugoloths.
Best Answer
I'm actually very familiar with the Dragonlance series as a whole, so I'll give you my perspective on this based on the source material being the Dragonlance series as a whole. To base it off of numbers, I'll use percentages of armies so you can easily incorporate it into your games.
Chromatic Dragons:
Black Dragons (5% to 7.5%) - moderately rare, confined mainly to swamp areas. They do serve in the dragonflight armies, although their presence is not as prominant as blues.
Red Dragons (5% to 7.5%) - Moderately rare, mainly independent breeds. Some reds are present in dragonflights, roughly to the same degree blacks are.
Green Dragons (0.01%) - Treacherous and vile, the greens in the books are not people friendly or team oriented. They don't work with the armies of Takhisis, and don't make for very good mounts due to their breath weapon being a chlorine gas that would murder it's own rider.
White Dragons (0%) - These are mentioned in the books but they're relegated to frozen areas and depicted as the most cowardly and small of the chromatic dragons. I keep checking the books but I can't find a single example of one seeing battle anywhere, so I would say a white would have to be of an unusual personality and unique backstory in order to be played.
Blue Dragons (80 - 85%) - These are the primary mounts of the evil armies. The blues are very, very similar to the Metallic dragons in that they are loyal and battle honourably. This is most prominently displayed in the post War of the Lance books where the entire planet unites to battle Chaos.
How many soldiers would you mount on dragons for a standing army? Approximately 10% to 15% of the standing army. This means if your cities are large, with an army of 3,000, then approximately 400 - 450 of them would be on dragons. From that, you would just apply percentages from above to get your final tally.
Assume 400 dragon riders. 320 would be blue, with the remaining 80 split between black and red. If a player wants a green or a white, I personally would need them to have a very compelling reason for that as it doesn't really fit the lore.
Metallic Dragons
Unlike the chromatics, the metallic dragons were evenly represented across the board. Because of this, I would recommend just doing a straight 20% split across all 5 breeds, Copper, Bronze, Brass, Silver and Gold. The number of dragons on the good side would be moderately less than the evil side (I would go with around 60% to 80% of the total evil dragons). This is based on the fact that the Draconians significantly reduced their numbers when they stole the eggs, the dragonlances were required to even the score, and the post Chaos war era with the dragon overlords almost totally obliterated them.
So this also depends on the era you choose to go with. I've broken down the presence of the dragons in the separate eras below.
Pre-Huma era - dragons equal
Huma era - dragons abundant on both sides
War of the Lance - Chromatic abundant, Metallic scarce, Dragonlance makes Metallic overpowered
Chaos War - Chromatic and Metallic in moderate amounts (due to prior war helping even the numbers), Chaos dragons overwhelmingly abundant and extremely powerful
Mina era - Chromatic dragon overlords present (with flights of chromatic dragons that are aggressive to other chromatics of differing colours), Chromatic dragons overwhelming but slaves and fiercly territorial, Metallic dragons almost extinct and in hiding.
Now you've asked for post War of the Lance. Contrary to other answers, the chromatics were NOT obliterated. They withdrew after Berem and his sister were reunited and the portal to the abyss closed. The chromatic dragonflights were still abundant as is evidenced by the systematic annihilation of the armies of good just prior to the Chaos war. This was a period just one generation after the War of the Lance as it dealt with the children of the Heroes of the Lance, including Kitiara and Sturm's son Steel Brightblade. Considering that the only thing that held the armies of darkness in check prior was their own infighting, when they instituted a knighthood in much the same manner as the Sword, Crown and Rose, they handily obliterated the good guys. With all things being equal, this is a clear indication of superior numbers at play.
So post War of the Lance you'd have a fairly even playing field for numbers, with superiority going to the good dragons with dragonlance riders. If you're twenty years past War of the Lance, this pendulum has swung to superior numbers in the chromatics again.
WotC forums has a guy who crunched some numbers for population, source thread here:
http://community.wizards.com/forum/other-published-worlds/threads/942146
Based on that, I would assume a 1000:1 ratio for humanoids to dragons to get a good, solid number. That will give you about 4,000 dragons to work with, of which I gave a sample randomization below that seems to fit with the story lines fairly well.
For metallic: I randomized 211 copper, 220 brass, 352 bronze, 521 silver, and 296 gold totaling 1,600 dragons.
For chromatic: I randomized 1,152 blue, 535 red, 481 black, 140 green and 72 white totaling 2,400 dragons.
This supports multiple armies of several thousand personnel outfitted with dragonflights of a couple hundred mounted riders per side. Since battles on that scale are limited to two or three standing armies at a time, that fits in with the lore fairly well while keeping things in perspective of post War of the Lance figures.