Battle of the Powers
For many years after the creation of the TwoTrees, the Valar dwelt in Valinor peacefully while Melkor was expanding his powers in Middle-earth, from Utumno his stronghold. When they finally came across the Elves who had awoken at Cuiviénen a few years ago, they decided to act against Melkor and protect the Firstborn.
For the first time, therefore, the Valar assailed Melkor and they came forth to war in all their might. The first assault was swift and easy and they threw away all his servants who fled to Utumno. Then the host of West set a guard over Cuiviénen, so that the Quendi learned nothing of the Battle of the Powers. Long and grievous was the siege of Utumno and many battles were fought before its gates. Middle-earth was sorely shaken in that time and its shape was changed.
In the end the gates of Utumno were broken and Melkor took refuge in the uttermost pit. Seeing that all was lost he sent forth his last servants, a host of Balrogs against Manwë, but they were scattered by the Vala. And Melkor stood at last alone. Tulkas stood forth as a champion and wrestled with him and cast him upon his face and bound him with the chain of Angainor. Then Melkor was brought to Valinor to be judged at the Ring of Doom.
Thus ended the first war of the West upon the North. Middle-earth had peace for some time. But this war, the Valar did on behalf of the Elves and Melkor never forgot it.