[Raynor]

Think of what might have been. Dragon-fire and savage swords in Eriador, night in Rivendell. There might be no Queen in Gondor. We might now hope to return from the victory here only to ruin and ash. But that has been averted - because I met Thorin Oakenshield one evening on the edge of spring in Bree. A chance-meeting, as we say in Middle-earth.'~Appendix A: Durin's Folk

I believe the context implies that Gandalf does not refer to other battles, synchronous with Pelennor Fields as saving these homes, but to his meeting with Thorin and the events at the time of the Hobbit that avoided all these disasters, considering also his reference to dragon-fire.

Originally Posted by Legate

the Eagles always come when they are needed, and this time they simply did not come. Ergo, the need was not that high this time.

True, but if they are an instrument of providence, as it is implied at least in the letters, their actions are probably dictated by foreknowledge, be it of Manwe or Eru. In my post I simply addressed the likely military importance of the eagles, should they have been there, as compared to their presence elsewhere.

This proves what I said, that on their own initiative the Eagles did not have the intention to come.

Hm, I am not aware that they knew. However, I agree with you that, if they knew, the logical explanation is that they chose to, or had to, pass this battle.