** Fall of Gondolin Section 3 Structure**

[Maédhros]

This is something that has troubled me for a long time:
From The Wanderings of Húrin

Yet there were ears that had heard the words that Húrin spoke, and eyes that marked well his gestures; and report of all came soon to the Dark Throne in the North. Then Morgoth smiled, and knew now clearly in what region Turgon dwelt, though because of the Eagles no spy of his could yet come within sight of the land behind the encircling mountains. This was the first evil that the freedom of Húrin achieved.

and we have from
The Tale

[On a time when Eärendil was yet young, and the days of Gondolin were full of joy and peace {(and yet Idril's heart misgave her, and foreboding crept upon her spirit like a cloud)}, Maeglin was lost. Now Maeglin loved mining and quarrying after metals above other craft; and he was master and leader of the Elves who worked in the mountains distant from the city, seeking for metals for their smithying of things both of peace and war. But often Maeglin went with few of his folk beyond the leaguer of the hills, though the king knew not that his bidding was defied; and so it came to pass, as fate willed, that Maeglin] {Now it so chanced that not long after Maeglin went to the hills for the getting of ore, and} straying in the mountains alone was taken [prisoner] by some of the Orcs prowling there, and they would do him evil and terrible hurt,

What does the leaguer of the hills means? Did Maeglin when we went to the Mountains went away from the area of the Vigilance of the Eagles?
How come they didn't notice that Maeglin and Co. had fled Gondolin?
In the tale, I have wondered if Morgoth moved an army from Angband to Gondolin, how come the Eagles didn't give at least a warning to the Gondolindrim?
Is that a problem with our version? Or can an explanation that I don't see can be found to this?