Dannebrog was 214feet long between perpendiculars, had a beam of 50feet and a draft of 23feet. The ship displaced 3057LT. She had a single steam engine that drove her propeller. The engine, built by Baumgarten & Burmeister, produced a total of 1150ihp which gave the ship a speed of 8kn. For long-distance travel, Dannebrog retained her three masts and was barque rigged. Her crew numbered 350 officers and crewmen.[3]
Sources disagree about the ship's armament; naval historians Paul Silverstone and Robert Gardiner say that she had sixteen 60-pounder guns,[3] [4] but Johnny E. Balsved shows her with a dozen 60-pounder, 88-cwt.,[5] guns, two 60-pounder, 150-cwt. guns, and three 18-pounder guns immediately after her conversion. All of these were rifled muzzle-loading (RML) guns. Balsved then shows that she was rearmed with six 60-pounder, 150-cwt. and eight 24-pounder guns, all RMLs, after 1865[6] while Silverstone gives her a later armament of six 8inches and ten 6inches RML guns. Dannebrog had a wrought-iron waterline armor belt thick and her battery was protected by armor plates of the same thickness.[3]
Dannebrog, named after the Danish national flag,[3] was built by the Royal shipyard in Copenhagen as a 72-gun sail ship of the line. She was laid down on 28 April 1848, launched on 25 September 1850, and commissioned on 17 May 1856.[6] The ship began conversion into an armored frigate on 21 May 1862 and the conversion was completed on 30 March 1864.[3] On 14 July 1864, she ran aground off Aarhus. She was refloated the next day.[7] Dannebrog had an uneventful career before the ship was stricken from the Navy List on 15 February 1875. The ship was converted into an accommodation ship that same year and served until she became a target ship on 30 May 1896. Dannebrog was broken up in 1897.[3] [8]
The figurehead of HDMS Dannebrog is now on display at the entrance to Marinestation København on Nyholm in Copenhagen. It has previously been on display in another location on the adjacent isle of Frederiksholm.