JR Potts, AUS 173d AB (Updated: 6/22/2016):
Her coal bins were designed to carry some 280 tons but, after construction, the area was actually limited to just 200 tons. This was deemed unacceptable so additional bin space was provided to hold an additional 20 tons. When the onboard coal ran was all used up, and a coal ship or resupply station was unavailable, the ship could revert to sail propulsion by way of two main masts. The coal could be stretched by using only one engine with the speed reduction lowering the maximum to 5.8 knots. The two boilers were not fitted below the water line as promised but were instead situated between the coal storage compartments and protected by the armor. Fully-loaded and armed, the vessel was a 1,535 ton ironclad ram.
The design resembled the first ocean-going ironclad that was also of French origin - launched in 1859 as the "La Glory". The newer sister ships were 187 feet long and their beam was out to 32.8 feet with the draught running at 14.3 feet. The two vessels were constructed by French L'Arman and consisted of the "Sphynx" (set aside for the CSS) and her sister ship, the "Cheops", which was in the process of being sold to Prussia. The French Government learned that the Sphynx was being built for the Confederate Navy and, being concerned about the political relationship with the current US Government, France blocked the sale in February of 1864. Denmark authorities became interested and purchased the Sphynx and also tried to acquire the Cheops because of their war with Prussia. Denmark was in a hurry and stipulated that the impending sale would require the Sphynx to be in a Danish port within 75 days. She was, therefore, completed and ready to set sail with a Danish crew as quickly as possible.
The Sphynx was renamed the "Saerkodder" (or "strong otter") by the Danish government and set sail for Copenhagen. The shakedown cruise exposed some early problems: she drew too much water - one foot aft and 6.5 inches on center line. The ship was well-built and was considered quite strong and her cannon were notably powerful. The engines were good, however, the Danish captain noted the armor plates being of minimum thickness and poorly fitted. The ship did not have enough room in the aft gun tower reducing the field of fire abeam. The design also did not fare well in high seas and, overall, her main deck had limited room leading to complaints from the crew about their general quarters. These problems lead to price-haggling between the Danes and L'Arman, ultimately resulting in negotiations breaking down. As such, the Danes ultimately refused to accept the Saerkodder in her current form.
Left without a buyer, L'Arman contacted the original buyers at the Confederate Navy which led to some clandestine meetings to arrange a purchase. On January 6, 1865 a Confederate crew came aboard at Copenhagen under the command of CSN Captain T. J. Page. At sea, the ironclad was recommissioned as the CSS Stonewall after southern General "Stonewall" Jackson. In need of supplies before setting out to hunt for Union shipping, the Stonewall returned to France. After being supplied for the mission ahead, she steamed for Maderia in the Azores for coaling before returning to American waters. En route a strong gale hit the ship and, as she maintained poor sea-keeping abilities, the resulting damage produced a leak. She was then forced to seek a safe harbor in Ferrol, Spain. The USS Niagara, a 5,540-ton steam screw frigate, accompanied by the USS Sacramento, a 2,100-ton steam screw sloop, were in port at the time and confronted the CSS Stonewall. A standoff was expected between the wooden-hulled US Navy ships and the CSS ironclad.
Having the leak repaired, the CSS Stonewall was eager for battle but could not corner the federal ships and, concerned about being bottled up in a foreign port, she left for the open sea once more. The Union ships followed at a safe distance and Captain Page turned to challenge the USS Kearsarge and the USS Sacramento only to see them turn and refuse the engagement. Stonewall then set sail for Lisbon, Portugal on March 24th, 1865 to resupply and take on new coal stores for the journey across the Atlantic. His first mission would be to target General Sherman's forces at Port Royal and protect South Carolina.