WORK to uncover Roman remains at St Loye's continues, and each day brings discoveries. Our earlier trial trenches revealed the top of an infilled well and we now have a second, though neither has yet been fully excavated.

It will be interesting to see what lurks at the bottom — wells have a useful tendency to attract things.

The wells though are possibly the least significant feature to have turned up in pairs. The latest phase of machine clearance has exposed another long section of V-shaped ditch, on a different alignment to our known defensive ditches.

Have we found a second fort? It looks like it, and further work should tell us more. Pottery fragments have been recovered from the clay and silt fills.

These will give a better idea of when the ditch went out of use. We already know it is later in date than our known fort, as it cuts through the remains of one of the barrack blocks.

There is still much to find out about our site, but we already know enough about the invasion to set the scene.

The fort builders will almost certainly have been battle-hardened troops operating in a hostile environment. We know serious battles took place not far to the east as the Roman army fought in modern Dorset to quell a tribe called the Durotriges, and it is unlikely that these troops arrived on the banks of the Exe without being in some way involved.

Resistance up till this point from the indigenous tribes had probably been firm, but it looks as if the Romans may have met particularly severe opposition as they to moved into what we now call Devon, land held by the Dumnonii.

The last few years have produced a surprising number of previously unrecognised forts near Exeter. A possible explanation for this relative density is the extent of initial, and perhaps protracted, hostility. In truth, we still know little about what actually went on as the army advanced westward.

The story started to unfold properly in 1971, when Exeter Archaeology, then the museum's Archaeological Field Unit, first exposed solid proof that a legionary fortress survived below the city.

Since then excavations by the unit have built up an impressive picture of this significant military establishment, built by the Second Augustan Legion some time in the mid 50s.

But what had the army been doing in the area before this, if anything? This key question has rumbled around the archaeological world for 40 years. Our new fort has the very real potential to throw some proper light on the subject.

So much hinges on dating evidence. Will our new fort be earlier than the legionary fortress? How long was it used? If we are lucky, answers will come from the pottery fragments discarded on site.

The other key question is who was involved. The Second Augustan Legion that built the Exeter fortress is elusive during its early years in Britain. We know they were present on the Isle of Wight, for example, before their commanding officer, Vespasian, left his post in 47, later to become Emperor. Debate still continues over what they did next. Could they have been involved in building our fort?

Quite possibly, although it will be very difficult to tell, and the legion was certainly not working in isolation. It is possible that our fort held a mix of legionary and other soldiers during this active and demanding stage of invasion.

Knowing who was involved would be useful. Unfortunately the evidence needed to identify our fort builders is likely to be particularly elusive — the best we might hope for is a stamped roof tile or the unit's name scratched on a soldier's bowl.

Obtaining a date for our first fort may be possible however, and the importance cannot be overstressed. If it can be shown to predate the fortress, it will represent the first military site in the region to do so.