of the campaign in May she was assigned to patrol the Mississippi River. During that month she grounded on a sandbar near Helena, Arkansas and could not be refloated even when some of her armor was removed due to the rapidly falling water level. As the water receded Osage began to hog at the ends because only her middle was supported by the sand. This caused her longitudinal bulkheads to split and broke many rivets in her hull and on her deck. She was repaired in place before being refloated at the end of November. After being towed to Mound City for more permanent repairs, Osage was transferred to the West Gulf Blockading Squadron on 1 February 1865 for the attack on Mobile, Alabama. She participated in the Battle of Spanish Fort, defending Mobile from the east, but struck a mine in a previously swept channel and sank rapidly on 29 March. Two crewmen were killed and some others wounded. The ship was later refloated and sold at auction at New Orleans 22 November 1867, along with three ex-Confederate ships, for $20,467. See also List of ironclads Notes References Neosho-class monitors Ships built in St. Louis Ships of the Union Navy