Battle of ThargelionBattle of Thargelion (375 Y.S.) - As Men came into Beleriand, Morgoth became fearful that they would make an alliance with the Elves, for he was unable to turn them all to his side.  So he decided instead to try and wipe them out.  His army met them at Thargelion.  This was the same place where the Elves and Dwarves first met.


"...but all the great land between Gelion and the mountains, and between Rerir and the River Ascar, was called by the Noldar Thargelion, which signifies the land beyond Gelion, or Dor Caranthir, the Land of Caranthir (who is the son of Fëanor); and it was here that the Noldor first met the Dwarves..." ~The Silmarillion, chap. 14 (Of Beleriand and its Realms)


And it was also here that the army of Morgoth first met the host of order to destroy it.


"During this time, the Haladin (Second House of Men in Beleriand) remained in Thargelion and were content.  But Morgoth, seeing that by lies and deceits he could not yet wholly estrange Elves and Men, was filled with wrath, and endeavoured to do Men what hurt he could.  Therefore, he sent out an Orc-raid, and passing east it escaped the leaguer, and came in stealth back over Ered Lindon by the passes of the Dwarf-road, and fell upon the Haladin in the southern woods in the land of Caranthir.


"Now the Haladin did not live under the rule of the lords or many together, but each homestead was set apart and governed its own affairs, and they were slow to unite.  But there was among them a man named Haldad, who was masterful and fearless; and he gathered all the brave men that he could find, and retreated to the angle of land between Ascar and Gelion, and in the utmost corner he built a stockade across from water to water; and behind it they led all the women and children they could save.  There they were besieged, until their food was gone.


"Haldad had twin children: Haleth his daughter, and Haldar his son; and both were valiant in the defense, for Haleth was a woman of great heart and strength.  But at last Haldad was slain in a sortie against the Orcs; and Haldar, who rushed out to save his father's body from their butchery, was hewn down beside him.  Then Haleth held the people together, though they were without hope; and some cast themselves in the river and were drowned.  But seven days later as the Orcs made their last assault and had already broken through the stockade, there came suddenly a music of trumpets, and Caranthir with his host came down from the north and drove the Orcs into the rivers." ~The Silmarillion, chap. 17 (Of the Coming of Men into the West)


After that, the race of Men were able to establish themselves well in Beleriand.