Still working on history of my world. So what would be good sources of information on Fomorian invasions of Ireland and wars connected to Fomorians?
Probably Wikipedia and like sites for a start. If you wanted to go deeper, I'm sure you could read the original sources for Irish myth. I believe the Mythological Cycle deals with them.
Already have a collection of links. But I found references to Fomorian invasions in several Irish legends, so I don't know which would be actually useful and which only mention them in passing. I found this: https://en.wikipedia.org/wiki/Cath_Maige_Tuired#The_Second_Battle_of_Mag_Tuired
Its obviously a myth rather than fact, but when i googled it i found six fairly definitive descriptions at the top of the first page