Hi Rhugga,
nice thread, this aspect has fascinated me too (any year now I'll get back to 'Battles of the Late Third Age' - possibly
) .
Fonstad's pretty good I think, but she's interpretation not canon! I suppose the only real information is in the Appendices of LoTR - I've not heard report of anything relevant in HoME?
IIRC there was a battle at the Fords of the Celduin. (Am I mis-remembering this? I think I need to re-read!). Then the Dale-men retreated to Dale, were defeated and holed up in Erebor.
The men of Dale ruled a wide land eastwards to the Celduin. Was Esgaroth independent or under the King of Dale by this stage?
Esgaroth was probably fairly secure against the Easterlings in the short term, with its famous easily-defended causeway (disregarding dragons of course!). On the other hand Erebor was no easy target! Maybe the Easterlings were motivated by the legendary gold and jools of the Lonely Mountain?
Thranduil, hmm tricky - could be he indeed took 20 days to get to Mid-Mirkwood, presumably pursuing orcs and fell beasts and despatching spiders etc. We know it was VERY tangled, and Bilbo & co. took ages and ages to cross the forest even with the aid of the elf path.