Short answers, pulled from the story.
Colchester became the first recorded town in Britain during the Iron Age as the capital of the Trinovantes tribe before the Roman invasion in AD 43. The town predates London by centuries and served as the primary target for Emperor Claudius upon the Roman invasion.
The Trinovantes joined the Iceni in the Boudican revolt of AD 60 and methodically destroyed the temple of Claudius in Colchester. The rebels massacred many thousands of inhabitants and the historian Tacitus estimated that 70,000 to 80,000 people were killed across the three cities destroyed.
The first known king of the East Saxons was Sledd who ruled in 587. Less reliable sources suggest Aescwine founded the kingdom in 527, but Sledd is the earliest confirmed ruler.
The Peasants Revolt broke out in Brentwood on the 1st of June 1381. Several thousand Essex rebels gathered at Bocking on the 4th of June before dividing to head to London.
Tilbury Fort was chosen as the focal point of English defenses against King Philip II's Spanish Armada in 1588. Queen Elizabeth made her famous speech to the troops gathered at Tilbury where her forces were positioned.
The Dunmow Flitch Trials appear to have achieved significant reputation outside the local area by the 14th century. The author William Langland mentioned the ceremony in his 1362 book The Vision of Piers Plowman.