[Zigûr]

The Black Speech was devised "in the Dark Years" (Appendix F), thus in the Second Age, so it doesn't really have much to do with the original breeding of Dragons, which took place in the First Age.

Originally Posted by Inziladun

I don't have my books handy, but I think there's a passage in the ROTK Appendices that discusses the Black Speech and its relative obscurity in the Third Age. I do seem to recall a passage stating that only the Nazgûl really remembered it by the time of the War of the Ring.

Quite right. This is what is said:

It is said that the Black Speech was devised by Sauron in the Dark Years, and that he bad desired to make it the language of all those that served him, but he failed in that purpose. From the Black Speech, however, were derived many of the words that were in the Third Age wide-spread among the Orcs, such as ghâsh 'fire', but after the first overthrow of Sauron this language in its ancient form was forgotten by all but the Nazgûl.

I think some people are getting a bit confused. There's probably a good chance Sauron helped Morgoth to breed the dragons in the First Age, because he "was often able to achieve things, first conceived by Melkor, which his master did not or could not complete in the furious haste of his malice." (Morgoth's Ring) That, however, has nothing to do with the devising of the Black Speech, which occurred in the Second Age, long after any possible dragon-breeding days of Sauron's.

At least, that's how it seems to my mind. I don't recall any evidence of Sauron having anything further to do with dragons after the First Age apart from a possible alliance with Smaug which never came to fruition. To be fair, there is some evidence in "Of the Rings of Power and the Third Age" that in the Second Age Sauron "gathered again under his government all the evil things of the days of Morgoth that remained on earth or beneath it" so I suppose it's possible he had under his command such dragons as survived the War of Wrath, although I do not believe we have any direct evidence of this. The fact that they went on to breed in the North beyond the Grey Mountains, far from Mordor, suggests that if any dragons did obey Sauron in the Second Age their allegiance was quite limited. It in fact suggests to me that Sauron did not command Dragons; it seems more probable that they never left their ancestral habitations in the North but rather bided their time, which would explain their prominence in the First and Third Ages, but not the Second.