There is another source of help that the Valar provided to Middle Earth that people have neglected to mention. After the two trees die, the Valar take the last two fruits from the tree (the sun and the moon) and set them in orbit around the world.

This one action basically ended Morgoth's plans to dominate MiddleEarth. Morgoth and his twisted servants could not tolerate the sun and were limited to hiding underground or around their vast volcanic dungeons where the volcanic dust would block the sun. Morgoth himself hated the sun and could not bear it, neither could the orcs. Essentially this one act put a huge handicap on his plans to dominate the Earth. He still ultimately conquered Beleriand but it required the help of the dragons and evil men to accomplish this. Nonetheless it was a hollow victory for Morgoth who was now essentially trapped underground - hardly an impressive stature for the 'lord of Arda'

There is another source of help that the Valar provided to Middle-earth that people have neglected to mention. After the two trees die, the Valar take the last two fruits from the tree (the sun and the moon) and set them in orbit around the world.

This one action basically ended Morgoth's plans to dominate Middle-earth. Morgoth and his twisted servants could not tolerate the sun and were limited to hiding underground or around their vast volcanic dungeons where the volcanic dust would block the sun. 
Morgoth himself hated the sun and could not bear it, neither could the orcs. Essentially this one act put a huge handicap on his plans to dominate the Earth. He still ultimately conquered Beleriand but it required the help of the dragons and evil men to accomplish this. 
Nonetheless it was a hollow victory for Morgoth who was now essentially trapped underground - hardly an impressive stature for the 'lord of Arda'