In 1648, Essex was the scene of a major military campaign of the Second Civil War. This essay seeks to explain why that campaign was fought. There are several reasons why such an investigation is worthwhile. Firstly, it challenges the fashionable historical idea that the Civil Wars were fundamentally a conflict between centre and localities. Secondly, it concentrates upon the Second Civil War as a serious proposition, not as a pathetic appendage of the earlier conflict to be dismissed with contempt but not consideration. Thirdly, it demands a look at Essex as a county caught up in the violence of civil war.