sentences:  His route was dictated by the desire to minimise the amount of open country favourable to cavalry operations he would have to pass through, and took him north of Oxford via Aylesbury and Bicester and then across the Cotswolds.At the beginning of September Essex was due north of Oxford with an army of some 10,500 infantry, no more than 4,500 mounted troops and an artillery train that is estimated at no more than 50 guns.Mining was now the principal tactic by which the Royalists hoped to bring the siege to a successful conclusion.