late Roman Dished Shields

[caiusbeerquitius]

Wouldn't the rim have been extremely irregular if originally dished?

No not if the shield would have been raised at the centre for between 5 and 8 cm. In this context it is more sensible to not look at shield boards preserved in a humid environment. Rather look at the shield bosses.

Quoting Robert Vermaat: "when in time and with enough skills available, dished shields would have been made and used, but when in times of crisis, hurry, and desperation flat shields would have been the simplest, fastest and easiest option to make."

I disagree: The shields were constructed of planks. These had to be individually sawn and plained. For the craftsman it makes basically no difference to make a slightly different form, it needs not more time, but gives a greater advantage to the user. Try it out.