The Earl compelled the Earl of Essex to surrender Lostwithiel, and was wounded at both the first and second battles of Newbury. While some claim Ruthven's faculties had begun to decay, Ruthven had lost favour of his military inferior, Prince Rupert whose arrogance he detested. They fell out on route to face down the Army of the Solemn league and Covenant commanded by his friend Alexander Leslie. Believing Rupert inept, Ruthven returned to Oxford leaving Rupert in command. The prince lost the battle to Alexander Leslie and his English parliamentary allies on 2 July 1644. Ruthven thereafter served as Chamberlain to the Prince of Wales having finally given up field service.