Can Triari from different legions band together to form TUGs - for instance. in Pacto, where you have 8 Hastati/Principes bases (4 TUGs) can you form the Triari into a 2 base unit -ergo, in Magna 16 bases forming a TUG of 4 Triari? Thank you!

You can.  It is not clear if this actually happened or not. 

Richard

Thank you. I was viewing them more as a converged grenadier battalion. Do accounts mention how far back Triari were usually placed behind the principes and hastati (if not back at the camp)?

Quote from: Brucka on September 24, 2020, 05:18:24 AM
Do accounts mention how far back Triari were usually placed behind the principes and hastati (if not back at the camp)?

I cannot find any description of how far back the triarii stood.

Richard

I believe it was around 250 feet from the front. I don't have references. I was doing some reading on this topic the other day.
Something like:

Velites
->30 feet
Hastati (themselves 6-8 ranks deep 25 feet)
->75 feet
Principe (themselves 6-8 ranks deep 25 feet)
->75 feet
Trarii

There would be gaps between every element of a Roman formation, including between maniples.
75 feet is most likely a best guess from the historian I was reading, but it's reasonable.
that would allow two maniples of men 25 feet deep each to have some space between them. It would still be pretty tight, and might well have been a bit bigger in terms of spacing.

It was also mentioned that while most of the Velites would have retired to the rear, some would perhaps linger in the 'empty space' between formations to continue skirmishing in relative safety with their legionary comrades close by, which I thought was interesting.