Prior to delivery, however, a shipyard clerk walked into the U.S. Minister's office in Paris and produced documents which revealed that Arman had fraudulently obtained authorization to arm the ships and was in contact with Confederate agents. The French government blocked the sale under pressure from the United States, but Arman was able to sell the ships to Denmark and Prussia, which were then fighting on opposite sides of the Second Schleswig War. "Cheops" was sold to Prussia as , while "Sphinx" was sold to Denmark under the name "Stærkodder" on 31 March 1864.