Melkor destroys the Lamps of the Valar
Event Type: Military/Strategic
But Melkor... assailed the lights of Illuin and Ormal, and cast down their pillars and broke their lamps. In the overthrow of the mighty pillars lands were broken and seas arose in tumult; and when the lamps were spilled destroying flame was poured out over the Earth. And the shape of Arda and the symmetry of its waters and its lands was marred in that time, so that the first designs of the Valar were never after restored.
The Silmarillion, Quenta Silmarillion, Ch 1, Of The Beginning of Days
Through long ages... all Middle-earth lay in a twilight under the stars. While the Lamps had shone, growth began there which now was checked, because all was again dark.
The Silmarillion, Quenta Silmarillion, Ch 3, Of The Coming of the Elves and the Captivity of Melkor
Elena Tiriel 1May10