Roman Helmet Types for then Dacian Wars?

[Darrell Hindley]

Hi,

My name is Darrell and I'm a wargamer and most certainly not an expert on the EIR 

What I wanted to ask is:

i/ What type of helmet was used at the beginning of the Dacian Wars?

ii/ The helmet's were reinforced, but at what point in time? During the Wars?

Thanks