Quote Originally Posted by EB
{celtic_infantry_gaesatae_descr}
Elite
Impetuous
Frightens Infantry
Very Hardy
Expert at Hiding in Forests

The Gaesatae (Guy-sah-tay; "Spearmen") are easily one of the most fearsome groups of warriors in the known world. They fight stripped bare but for neck torcs and sometimes their shoes or boots. They fight with longswords, but are named for their incredible skill with javelins; they can hurl them unnaturally long distances and deal great damage with them. Their charge is most ferocious though, causing many lines to simply fold and flee. This is not all solely due to skill and strength, though they are experienced and huge, muscular men. They imbibe a chemical before battle making them seemingly impervious to pain. They will fight to the very end, and are very destructive when employed properly.

Historically, the Gaesatae were Gallic naked religious fanatics. Their skill was a source of terror, and their frightful appearance shook many. Most horrifying, even beyond their size and skill and terrifying cries, was their seeming invincibility. A chemical they used allowed them to brush off and ignore any pain. They were remarked to do things such as rip javelins that had struck them free from their bodies, and hurl them back, and continue to fight with gashes and wounds that would have surely fell a normal man. They were Hannibal's favored Gallic mercenaries, and were used as his personal guards, as they were so devoted and trustworthy, as well as brave and skilled.

{celtic_infantry_gaesatae_descr_short}
Gaesatae are an elite, infantry-killing shock unit - one of the most fearsome in the ancient world.
In EBH Teutatis is also mentioned in connection with them, and that they were people who "abandoned their tribal heritage to seek fortune, glory and heroic death". I don't know why this information was omitted, but I haven't read the whole discussion, and it could have been decided that it wasn't accurate for all of them, or some other reason for not including it.