In 1659, Bruce acted as a messenger between General Monck, Cromwell's commander-in-chief in Scotland, and the exiled King Charles II. A passport survives, issued to Bruce by Monck in September 1659, and giving him permission to remain in Scotland until his "returne to Holland," and it appears that the messages he brought from Charles persuaded Monck to march his army to London, a decisive event in the Restoration. The nature of their communications is not known, although it would appear that Moray selected him for the task. Sir Robert Douglas stated that Bruce "painted the distress and distractions" of Scotland before the General, and suggested to him "the glory that would be acquired in restoring the royal family."