At the end of the Second Age, the Númenórean king Ar-Pharazôn built a huge fleet with the intention of invading Valinor and taking immortality by force. They sailed West until they successfully landed in the Undying Lands, at which point the Valar (according to the LotR Wiki) immediately "laid down their guardianship of the world and called upon Eru" for aid.
Now, putting aside the question of whether immortality could in fact even be taken by force (if anyone has any information on that please share, but I'm assuming a certain mythological suspension of disbelief there, akin to Pandora keeping "hope" in a box), are we supposed to believe that the Númenóreans seriously built a fleet strong enough to essentially conquer heaven?
I know the Valar may or may not be gods, but they are undoubtedly beings of incredible power. Plus, you know, there are a bunch of them. Was the host of Men truly powerful enough that the Valar gave up their custody of the entire world and appealed to the greatest source of power in the cosmos, before even meeting them in battle?
Or was there another reason that Eru was called upon, aside from the overwhelming might of Ar-Pharazôn's force?