De Soto was a sidewheel steamer, one of the many taken over by the Confederate forces for use on the Mississippi and other rivers. In April of 1862 she was busy ferrying troops to evacuate the area near Island No. 10 and was used, under a flag of truce, to communicate with the Union gunboats. On 7 April 1862 she carried Confederate officers who surrendered possession of Island No. 10 to Flag Officer Foote. It was at night, and De Soto approached cautiously, giving four blasts of her whistle, repeatedly, until answered, whereupon Federal officers came on board to accept surrender.
She then became USS De Soto, with a later name change to General Lyon.