Himring

[Makar]

I am having trouble visualizing how Maedhros defended his realm, especially after the Dagor Bragollach, when the enemy was active all around him. As far as I know, all he controlled were the hills of Himring and the fortress itself. Is it fair to speculate that all the folk of Maedros dwelt within the fortress? I am not familiar with Noldorin housing. Do you think it would have been mostly underground, like Nargothrond? If they lived only in the fortress, how were the hills still held and why was the fortress not under siege the entire time span between the Fourth and Fifth battles?

[Thinlómien]

I suppose it's not mentioned anywhere, what was his place in Himring like unless it's mentioned in HoME.
I'll let someone, who knows (and remembers) more answer you...

[Turin]

The Sil is a bit vague on this sort of thing but there are a couple of hints:

Maedhros is said to have done "deeds of surpassing valour" during the Dagor Bragollach. He was an Amanian elf, as well as being the son of the greatest elf of all time, so he must have been very powerful in his own right. The Sil doesn't go into too much detail because it is not really within the main purpose of the story; which is to describe the breaking of the Seige of Angband, and how Morgoth's armies began to overrun northern Beleriand. Although, evidently it must have been a great deed since Tolkien makes a special mention of Maedhros' valour. Himring was quite isolated and looked down towards large areas of plain, making it quite vulnerable.

Without being able to refer to my book, I think that Maglor held the Gap, and when he was being overrun, he fled to Himring and reinforced Maedhros' people. The Feanorians were quite fortunate in the sense that most of the major assaults (even before the breaking of the seige) tended to be focused around Hithlum and the sources of Sirion, including Anfauglith. They may have been able to increase their numbers because of their relative stability, and were probably better prepared to withstand attacks from orcs: they were able to flee to the hills, so Maedhros' people could withstand the volcanic ash that issued from Angband, as well as have the higher ground during the actual battles.

[Aiwendil]

It seems to me that Maedhros actually had a fairly good position on Himring. From "Of Beleriand and its Realms":

The chief citadel of Maedhros was upon the Hill of Himring, the Ever-cold; and that was wide-shouldered, bare of trees, and flat upon its summit, surrounded by many lesser hills.

So the terrain surrounding Himring was very hilly and probably quite rugged; Maedhros may well have had rangers patrolling them, or even forts or other defensive structures hidden among them. Himring itself could probably be defended quite well by stationing troops in a circle around its summit. Maedhros would have the advantage of high ground and his archers would be in an excellent position. Also, we have no idea how extensive his fortifications were. There may have been outer defenses on the slopes of the hill.

Of course, regardless of his situation on Himring, Maedhros was in a difficult spot after the Bragollach. The passes on either side of the hills, which his brothers had previously held, were taken in that battle, and he could be easily surrounded. Perhaps if Morgoth had launched an intensive assault Himring would have fallen. But Morgoth did not. I don't think that Himring itself mattered very much to Morgoth's strategy in the east at this point. What he wanted in the Bragollach was to open a pass into Beleriand; and he accomplished this by taking both the Pass of Aglon and the Gap of Maglor. Unless Maedhros had the power to really harass any Orcs coming through those passes (and apparently he did not), capturing Himring itself would have been unnecessary.

[Rumil]

This reminded me of an old thread where its mentioned that Himring still survived into the Third Age

Himling - Himring

Perhaps even the sole hobbit mariner had a look at it ?