Very quickly.
Less than one-tenth of the elves in the forest were left.
The elven army, which had far more numbers than the dragons, had already been defeated. The remaining elves showed a different performance in the war and the approaching death.
Some of the elves fled in a panic, hoping to live a little longer.
Some of the elves were willing to die, and they fought with the true dragons while being bathed in blood.
Some of the elves were trembling and mumbling to themselves.
Some of the elves stood rooted to the ground as if they had lost their souls. Their eyes were blank, and they were at the mercy of others.
...........
The corpses of those who died from fire, frost, Dragon Breath, claws, swords, spells, and other attacks were everywhere. Flames were rolling, black smoke was billowing, and the smell of burnt corpses filled the air.
It was clearly the Prime Material Plane, but this scene was like hell.