Porting dragon subdual rules from AD&D 1e to D&D 5e?

Question

I do not know the rules of AD&D 1st edition that were in effect around 1987. I own, however, a copy of the Forgotten Realms Campaign Set (TSR1031). I've just noticed (after all these decades :D) that its DM's Sourcebook of the Realms has alternative rules for subduing a dragon (on p.15): it can't simply be subdued, it must be awake and challenged properly, and it must accept the challenge before subdual as per the general rules can happen. So... there must have been general rules for subduing a dragon.

What were the general AD&D 1st edition rules for subduing a dragon, and how would those rules best be ported to D&D 5e, if they're worth porting at all?

Answer 1

Subduing in 1st Edition

In AD&D (1st Edition), the rules for subduing a dragon were found in the Monster Manual I, under the DRAGON entry:

Subduing a Dragon: An attack on a dragon to subdue, and thus capture it may be opted for if such intent is announced in advance of the combat. Silver, gold, chromatic and platinum dragons cannot be subdued. (Monster Manual, 1st Edition, p. 30)

It is worth noting that in that edition, "chromatic" wasn't the generic name for evil (and coloured) dragons, but the name of Tiamat, the 5-headed dragon, ruler and mother of all evil drakonkind.

The mechanic was then described :

• All points of damage scored by attacks upon the dragon are considered non-fatal.
• The total number of HP scored each round is stated as a percentage, ratioed over the HP the dragon had at the start of combat (i.e. 10 damage done to an adult Black dragon with 40 max HP give a 25% chance to subdue the creature on that particular round).

Then the page goes on with details on the maximum number of attackers possible given the size of the dragon, the value of a subdued dragon in a city and the length of subdual.

Yes, 1st Edition dragons had much fewer HPs than they have in 5e! But so did the PCs...

Subduing in 5th Edition

In 5e, subduing a dragon seems much harder, if even possible.

First, the very nature of dragons (Creatures of ego) make them tough customers for subdual :

Trying to humble a chromatic dragon is like trying to convince the wind to stop blowing. (Monster Manual, 5th Edition, p. 86)

Second, every type of dragon has a distinctive relationship with power, hierarchy and slavery. It's up to the DM to decide if any endeavour of subdual is bound to succeed or fail. Sometimes, guidelines are given in the description of a specific dragon.

For example, Black dragons usually fight to the death if they can't escape :

On the verge of defeat, a black dragon does anything it can to save itself, but it accepts death before allowing any other creature to claim mastery over it. (Monster Manual, 5th Edition, p. 89)

Green dragons are more subtle :

Any creature foolish enough to attempt to subdue a green dragon eventually realizes that the creature is only pretending to serve while it assesses its would-be master. (Monster Manual, 5th Edition, p. 95)

White dragons, finally, seem the most prone to subdual, but only by powerful creatures (which is open to interpretation), and there are consequences:

Powerful creatures can sometimes gain a white dragon's obedience through a demonstration of physical or magical might. Frost giants challenge white dragons to prove their own strength and improve their status in their clans, and their cracked bones litter many a white dragon's lair. However, a white dragon defeated by a frost giant often becomes its servant, accepting the mastery of a superior creature in exchange for asserting its own domination over the other creatures that serve or oppose the giant. (Monster Manual, 5th Edition, p. 102)

TL;DR : there is no proper subdual mechanic in 5th Edition. Dragons are hard to enthrall, due to their ego. DM must assess the reaction of each dragon, based on it's type and characteristics, which are given in the Monster Manual.

Answer 2

In AD&D (1e MM p. 30) -- which wasn't called 1st Ed. until 2nd Ed. came out -- all characters attacking a dragon had to declare that they were striking to subdue, rather than kill (the text talked about "striking with the flat of swords"). They would then attempt to survive the process of either reducing the dragon to zero hit points without any killing attacks, or winning a percentile die roll based on remaining HP divided by dragon's total HP. If they succeeded, "due to their cowardly nature", any dragon (but not silver, gold, chromatic, or platinum) could be subdued and would accept servitude. I recall a clause whereby, if "mistreated", the dragon might break its subdual (usually at the worst possible time, of course).

There were actually rules in AD&D specifying how many characters could attack a dragon of a given size, based on one per three linear feet on each side; these were mainly used for subduals, in my experience.

In OD&D, this was normally something you'd only attempt if you found the dragon sleeping, as the initial surprise attack was almost the only chance a reasonably sized party of less than "name" level adventurers had of surviving the attempt with a dragon more powerful than "small, young".

OD&D (Monsters and Treasure p. 12, Subduing Dragons):

When intent to subdue is announced hits scored upon the Dragon are counted as subduing rather than killing points. Each round of melee the number of points scored in hits is ratioed over the total number the Dragon has (hit point total), the hits obtained being stated as a percentile of the total possible, i.e. 12%, 67%, etc. The percentile dice are then rolled to determine if the Dragon has been subdued. A roll equal to or less than the percentage of hits already obtained means the Dragon is subdued.