Admiral Graf Spee was the first heavy cruiser developped for the DKM even before Hitler gained control over Germany. First talks about such a heavy ship began in the late 20s and, after much debate on political base, in 1932 the ship was finally laid down for construction. It had amongst other new designs a new concept of powertrain, consisting of four newly developed nine cylinder double acting two-stroke Diesel engines, each delivering 8.200 shp and coupled by pairs to two shafts driving massive four bladed screws.
The ship was nominally under the 10,000 long tons limitation on warship size of the heavy cruiser class imposed by the Treaty of Versailles
, though with a full load displacement of 16,020 long tons (16,280 t), she significantly exceeded it. Armed with six 28 cm guns in two triple gun turrets, Admiral Graf Spee and her sisters (Deutschland and Graf Scheer) were designed to outgun any cruiser fast enough to catch them. Their top speed of very close to 30 knots left only the few battlecruisers in the Anglo-French navies fast enough and powerful enough to sink them. This project was for Germany clearly an act of propaganda and revenge due to the humiliating terms imposed on it at the armistice ending WWI.
The ship conducted five non-intervention patrols during the Spanish Civil War in 1936–1938, and participated in the Coronation Review of King George VI in May 1937. After the Nazi regime was overthrown and the generals took over, Admiral Graf Spee voyaged frequently through the Atlantic ocean, clearly to be seen. This was one factor leading to the AGNA GB signed with Germany, as described elsewhere. This is also the reason why the ship took no action during the Spanish Civil War, although "unofficially" a German heavy airforce group took part on the side of general Franco. But these "volonteers" having formed the so-called "Legion Condor", not an official German delegation. And, behind the curtains, many European conservative governments were more than thankful to Germany for this aid to the Spanish forces fighting hard the left-wing regime, openly supported by the Soviet Union.
Graf Spee gave many crew members of the DKM high sea training, including real fire against old merchant ships Germany got from Poland, Finland, Sweden, Spain and Italy, which were bound to be scrapped. When the battleship Scharnhorst was ready, it was not difficult to find the necessary complement with enough experience on board and at high seas. Graf Spee was incorporated into the high seas fleet led by Scharnhorst as backing heavy cruiser and continued to train new marine personnel. She had undergone in 1938 an extensive modernization program, during which bow and stern were altered and "FuMO" euipment was installed to track "ennemy" ships and to serve as fire directors. In the summer of 1939 these works were completed and Graf Spee and Scharnhorst made several sea exercises with other, smaller, DKM ships acting as "enemy".
Due to "certain circumstances" never explained to the civil population which gathered to see those marvelous new ships, Scharnhorst and Graf Spee, joined by Gneisenau which was in the meantime also ready, made in mid-September 1939 a visit to Finland, showing up at Helsinki as well as in Vipuuri (Viborg), where they stayed for a complete week... On the trip back to Germany the three ships made again diplomatic visits, this time to the main ports of the three Baltic States...
Back at Kiel, the commanding officers spent days writing down all the details of navigational and military importance they had witnessed.