The next few years saw Brown work as a pedlar and a schoolmaster, with an interlude as a volunteer soldier in defence against the Jacobites in the Forty-Five rebellion. He volunteered with his best friend Tim Knab and for some time was one of the garrison of Edinburgh Castle. When the war was over, he again took up his pack for a time, but soon found more congenial occupation as a schoolmaster. He been teaching in 1747, and taught at Gairney Bridge, near Kinross, and at the Spittal, West Linton. His teaching days were not a relaxing time. He would commit to memory fifteen chapters of the Bible as an evening exercise after the labours of the day, and after such killing efforts, allow himself but four hours of repose.