Xenosaga: What exactly happened on Miltia 14 years ago?

Question

What exactly happened on Miltia 14 years ago? Why did the war between the federation and the Immigrant fleet start anyway?
Does anyone know what the Zohar really is?

Answer 1

First off, play Xenosaga I, then II, then III.
The Zohar is the object that poseses the entity known as U-DO.
Next, the fight started because the two groups were bumping heads over the Zohar. I'm pretty sure that's happened. It's been along time since I've beat all the Xenosaga's, but I'm sure that's why they were fighting.