In AD 43 the Roman Emperor Claudius staged a successful invasion of Britain and most of the country fell under Roman control. At the time most of Essex was part of the territory of the Catuvellauni, an Iron Age tribe, led by Cunobelin, who had taken over the lands of the Trinovantes tribe, who had their capital at Camulodunum (Gosbecks, Colchester). A legionary fortress built at Colchester was redundant by AD 49 and became a colonia for retired legionaries and their families, dominated by a temple to the Emperor, where he could be worshipped as a god.
In 60 AD Boudicca, Queen of the Iceni tribe (based in Norfolk) led a revolt against the Romans, which the Trinovantes of Essex rapidly joined. Colchester was burnt to the ground and the inhabitants massacred, and this was followed by London and St. Albans. After the Boudiccan revolt had been suppressed, in 61 AD, Colchester was rebuilt as a showpiece town, named Colonia Victricensis or City of the Victorious, this time with substantial walls as defences.
The Essex landscape gradually altered as the native Britons adopted Roman styles of building and Roman ideas, whether by choice or through imposition. The networks of roads and towns, the wide variety of imported goods, and the changing patterns of administration have all left their mark on Essex. The later Roman period, by contrast, appears to be one of decline. At Chelmsford the town contracted in size, and crops were being grown within the walls of Colchester.