Christian IV (12 April 1577 – 28 February 1648) was the king of Denmark and Norway from 1588 until his death. He is sometimes referred to as Christian Firtal in Denmark and Christian Kvart or Quart in Norway.
Christian IV aligned with the League of Ostend, and warred against Gustavus Adolphus and the United States of Europe from 1633 through 1634. Christian feared the threat a powerful Sweden posed to Denmark, as Christian wanted to restore the Union of Kalmar with Denmark at the center.
Christian had much the same charisma as his Swedish counterpart, Gustavus Adolphus, and was widely known as a heavy drinker, but always appeared sober despite his large consumption. Christian was generally enthusiastic about new technologies, and quickly warmed to Grantville's marvels, despite their status as enemies. Christian financed a research and development department dedicated to creating new weapons based on knowledge gleaned from Grantville's up-time books and commissioned his son, Ulrik, to head the department. However, Christian's decision to fund such a project was risky as Denmark was on the brink of an economic crisis. Some of these innovations were too impractical to construct, such as an incomplete submarine built for royal luxury and a diving suit. The latter proved to be fatal when the air hose ruptured during a test and the suit lost pressure. The results were so gruesome that Christian thought of using the suit as an execution device. The only innovations that Christian's department had successfully achieved were spar torpedoes and water mines.
Christian had paid for a complete copy of the most recent edition of the Encyclopedia Britannica that Grantville had. This made it possible for Ulrik's assistants to check the various names Eddie Cantrell had given, and to reveal that Eddie had been lying. This discovery caused an angered Christian to sentence Cantrell to the Blue Tower.
Following Denmark's dual defeats at the Battle of Luebeck Bay and the Battle of Copenhagen in 1634, Christian reluctantly surrendered to the USE, officially becoming its ally. His fear that Denmark would be a junior partner in the Union of Kalmar also came to pass. However, Denmark was allowed to keep its sovereignty. As a sort of bonus, the USE established an air force base in Denmark; Christian was overjoyed, and insisted that he wanted to fly an airplane himself. He, or at least the Union, also received an ironclad; the SSIM President, rechristened the Union of Kalmar.