Roman strategy gave the future site of London a significance that it had not had before. Sixty miles to the north-east was Colchester: first a legionary fortress, then a colony for retired soldiers. Twenty miles to the north-west was St Albans (Verulamium), and fifty miles to the south-east Canterbury (Durovernum Cantiacorum). Both these places were important tribal centres that became Roman towns.
The highways connecting them had to cross the Thames, and London was where the river was narrow enough to be bridged yet had sufficiently high ground, especially among the marshes on the south bank, for the construction of approach roads.
To this point the Thames was tidal, enabling large cross-Channel ships to sail up-river, bypassing the Kent ports and delivering troops, supplies and goods closer to where they were needed.
The Romans’ original choice of crossing point may have been about a mile further west, for the St Albans and Canterbury roads are aligned in the direction of Lambeth-Westminster. No bridge or harbour works have been found here, however, and the plan must soon have been abandoned. Some items of military equipment from that period have been found in the Thames.
By AD48, just five years after the invasion, construction was underway of the street that would form the east-west axis of London, while on the south bank of the Thames, the incoming roads were being re-routed to cross near today’s London Bridge.
Publius Ostorius Scapula succeeded Aulus Plautius as governor in AD47 at a time when London was just beginning. After forcefully settling a revolt of the Iceni in AD47, he spent his time in Britain campaigning in Wales. He established a colony of veterans at Colchester in about AD49 and founded a fortress at Gloucester for the 20th legion. He died at the age of 52 while on campaign and a new governor had to be hastily appointed to bring the situation under control.
According to the Roman historian Tacitus, however, these commanders, as the first two governors of Britain, transformed the south-east of Britain into a regular province.
It is likely that London’s earliest military bases would have been established to watch over the river crossing. In Southwark, the two roads which converge just south of the crossing were not built until about AD48, since the main invasion route probably crossed further west, near the present Westminster Bridge.
Even though the dating of wooden structures on the north bank has brought the date of the foundation back to as early as AD47, it is highly likely that the bulk of the army would have advanced further inland by then.
In Southwark early military activities would have included road building on the marshy terrain (207BHS72) and such associated engineering schemes as land drainage and the bridging of the channels between the islands in Southwark, in order to create a firm foundation for the burgeoning road system. The evidence may suggest the possibility of Southwark being a depot concerned with the military needs of an army engaged in conquest and with providing for the military administration established in early London.
From the evidence of the small finds and the large preponderance of copies of Claudian coins, there seems to be little doubt that there was some sort of military presence at the southern end of the Thames crossing, although indisputable structural evidence belonging to it has yet to be identified.
There was also a possible northern encampment. At St Swithins House, Walbrook (WAO06) a pair of V-shaped military ditches were found to have been filled in as early as AD50. The location of the ditches fits with a suggestion that a military enclosure may have been established post-conquest to protect the bridgehead. These ditches had later been widened but had gone out of use by the time of the Boudican revolt.