After the victory at Lostwithiel, King Charles first probed the Parliamentarian defences at Plymouth then marched back across the southern counties of England to relieve several garrisons (including Banbury, Basing House and Donnington Castle, near Newbury), which had been isolated while he had been campaigning in the west. King Charles was joined briefly by Prince Rupert, who was ordered to march into Gloucestershire in an attempt to draw some of the Parliamentarian armies after him. The Parliamentarians, however, did not follow Rupert. As a result, the manoeuvre divided the Royalist forces, rather than those of Parliament.