The Roman fort initially founded around 79AD was probably about 2-3 acres in size with around 500 men garrisoned there. It would have consisted of a bank of clay, surmounted by a wooden stockade and surrounded by a ditch.
The tight military grip around Manchester may well have lasted only around 40 years as attention fell to the North and the subjugation of the tribes across the border. As additional garrisons were required north it is certain that the Garrison at Manchester’s near neighbour Castleshaw was probably abandoned and as problems continued Manchester’s Garrison could well have been reduced.
However some historians speculate that the Brigantes took advantage of the situation and rebelled in 150 AD. Two brigantian forts were destroyed around that time, one in Lancaster and a second at Birrens and troops may well have been moved back to Manchester.
This period saw the fort reconstructed using turf and timber and the return of the legions also gave Manchester its first economic impetus with iron production and smithying taking place around the area.
A national programme of replacement saw Manchester’s fort refurbished in stone around 200 AD which also saw industrial activity give way to domestic building but by the end of the 3rd century, the civilian town was almost deserted.
By around 350 AD THE XXth legion had been withdrawn from Chester. We have no evidence of when the Romans finally left Manchester although we know its fort was under threat, a threat which came from the Irish Sea and substantial defensive ditches were constructed.
Coins proved that the there was still settlement around 400 AD but Roman rule finally collapsed at the beginning of the 5th century and Roman administration and forts simply ceased to exist.