On 22 February 1918, "Rheinland" and her sister "Westfalen" were tasked with a mission to Finland to support German army units to be deployed there. The ship arrived in the Åland Islands on 6 March, where her commander became the Senior Naval Commander, a position he held until 10 April. On 11 April, the ship departed the Ålands for Helsinki, with the intention of proceeding to Danzig to refuel. However, she encountered heavy fog while "en route" and ran aground on Lagskär Island at 07:30. Two men were killed in the incident and the ship was badly damaged. Three boiler rooms were flooded and the inner hull was pierced. Refloating efforts on 18–20 April proved unsuccessful. The crew was removed temporarily, to bring the pre-dreadnought back into service. On 8 May, a floating crane was brought in from Danzig; the main guns, some of the turret armor, and the bow and citadel armor were all removed. The ship was lightened by —more than a third of her normal displacement—and with the aid of pontoons, eventually refloated by 9 July. The ship was towed to Mariehamn where some limited repairs were effected. On 24 July the ship departed for Kiel with the assistance of two tug boats; she arrived there three days later. It was determined that repair work was impractical and instead the ship was decommissioned on 4 October and placed into service as a barracks ship in Kiel.