The lands of the canton of GraubÃ 1\/4 nden were part of the Helvetic Republic , but the `` perpetual ally '' of Switzerland became a canton in 1803 . In 1798 , the lands of the canton of GraubÃ 1\/4 nden became part of the Helvetic Republic as the Canton of Raetia . With the Act of Mediation the `` perpetual ally '' of Switzerland became a canton in 1803 .