Skirmish at Hithlum (155 Y.S.) - After Dagor Agalareb, the land lay relatively quiet.  Morgoth had not the strength to assault the Elves, nor could the Noldor enter his abode.  However, that did not stop each side from trying to harass the other.  The Noldor tried to shut the enemy in, but had too few numbers to complete the blockade.

 

"Nor could the stronghold of Morgoth be ever fully encircled; for the Iron Mountains, from whose great curving wall the towers of Thrangorodrim were thrust forward, defended it upon either side, and were impassable to the Noldor, because of their snow and ice.  Thus to his rear and to the north Morgoth had no foes, and by that way his spies at times went out, and came by devious routes into Beleriand.  And desiring above all to sow fear and disunion among the Eldar, he commanded the Orcs to take alive any of them that they could and bring them bound to Angband..." ~The Silmarillion, chap. 13 (Of the Return of the Noldor)

 

One exception to this uneasy peace was the conflict at Hithlum.  Morgoth could not muster a full army, and he tried to avoid the bulk of Noldor forces guarding his fort.  The result was a melee that could not qualify as a full-scale assault, but was more of a skirmish.

 

"When nearly one hundred years had run since the Dagor Agalareb, Morgoth endeavered to take Fingolfin at unawares (for he knew of the vigilance of Maedhros), and he sent forth an army into the white north, and they turned west and again south and came down the coasts to the Firth of Dengrist, by the route that Fingolfin followed from the Grinding Ice.  Thus they would enter into the realm of Hithlum from the west; but they were espied in time, and Fingon fell upon them aomg the hills at the head of the Firth, and most of the Orcs were driven into the sea.  This was not reckoned among the great battle, for the Orcs were not great in number, and only a part of the people of Hithlum fought there.  But thereafter there was peace for many years, and no open assault from Angband..." ~The Silmarillion, chap. 13 (Of the Return of the Noldor)