By 1646 the Royalist cause was in terminal decline.The Battle of Stow-on-the-Wold, the last pitched battle of the First English Civil War, was fought on March 21 1646. The victorious Parliamenty forces then set about capturing the last of the Royalist strongholds. Exeter and Barnstaple fell to Lord-General Thomas Fairfax, and after accepting the surrender of Oxford on June 24, Rainsborough took command of the Parliamentry forces besieging Worcester. During the months after the surrender of Worcester, all other Royalist strongholds fell to the Roundheads. The last to do so was Harlech Castle in Wales, which surrendered on March 13 1647.
The parliamentary forces placed their siege artillery on a small hill to the south-east of Worcester overlooking the Sidbury Gate. The largest piece in their train was "Roaring Meg" - a mortar that fired 200 pound shots. From there they were able to damage severely the city's medieval walls. In 1651 shortly before the battle of Worcester the hill was fortified by the Royalists and the remains of those fortifications are now in the park known as Fort Royal Hill.