Southern England: overview
Most of southern England remained Parliamentarian in sympathy throughout the English Civil War. The counties of Kent and most of Sussex were secured for Parliament during the summer of 1642. Hampshire was largely Parliamentarian at the beginning of the war, but the Royalists held a number of isolated strongholds in the county. Parliament moved swiftly to control the vital port of Portsmouth which was besieged and captured by Sir William Waller in September 1642. Waller then mounted a successful campaign to capture the Royalist strongholds of Winchester, Chichester and Arundel.
During the spring of 1643, the Earl of Essex marched against the Royalist capital Oxford. Although he captured Reading, Essex's campaign against Oxford faltered. He remained inactive for several months before marching for the relief of Gloucester in August. The King's army blocked Essex's route home and he was obliged to fight his way through to London at the first battle of Newbury in September 1643.
Royalist pressure in the region increased when Lord Hopton was ordered to advance through Hampshire, Sussex and Kent to threaten London from the south. Parliament appointed Sir William Waller commander of the Southern Association army to counter the threat. Hopton and Waller manoeuvred against one another during the winter of 1643 but the Royalist advance was finally halted by Waller's victory at Cheriton in March 1644.
After the inconclusive second battle of Newbury in October 1644, Parliament's war-effort was invigorated by the formation of the New Model Army. After Fairfax's stunning victory at Naseby in June 1645, the New Model invaded the Royalist-held West Country. During the autumn of 1645, Oliver Cromwell led a detachment to clear all remaining Royalist strongholds in the south. Cromwell's campaign culminated in the storming and sack of the fortress of Basing House in October 1645.