Charles XII of Sweden: King of Sweden (1697-1718)

(17 June 1682 – 30 November 1718)

Charles was an exceptionally skilled military leader and tactician as well as an able politician, credited with introducing important tax and legal reforms. As for his famous reluctance towards peace efforts, he is quoted by Voltaire as saying upon the outbreak of the war: "I have resolved never to start an unjust war but never to end a legitimate one except by defeating my enemies". With the war consuming more than half his life and nearly all his reign, he never married and fathered no children. He was succeeded by his sister Ulrika Eleonora, who in turn was coerced to hand over all substantial powers to the Riksdag of the Estates and opted to surrender the throne to her husband Friedrich of Hesse-Kassel, who became King Frederick I of Sweden.

Childhood and upbringing (1682–1697)

Charles (Karl) XII was born at Tre Kronor Castle in Stockholm on Saturday 17 June g.s. (June 27, n.s.) 1682 as the son of King Charles XI and Queen Ulrika Eleonora. He was the second in order of the royal couple's seven children, of whom only Charles and the sisters Hedvig Sofia and Ulrika Eleonora lived on to adulthood.

Charles was born with a victory hood, meaning part of the amniotic membrane remained on his head. On 12 July 1682, the young prince was baptized at the castle by the baptist Samuel Werenius. Prince Georg of Denmark, Duke Kristian Albrekt of Holstein-Gottorp and the Prince-Bishop of Lübeck were appointed sponsors. Old Queen Kristina was godmother together with Maria Amalia of Courland and Princess Sofia Dorotea of Holstein.

Ulrika Eleonora took a large part in her children's upbringing. From the mother, the young prince learned to say morning and evening prayers and various biblical stories. In 1686, the queen began holding public dinners with the children to get them used to the attention, and with her mother, Charles witnessed a major military exercise at Djurgården for the first time. As the oldest boy in the royal family, Charles was appointed crown prince. Charles XI ordered that he be given an extensive education to prepare him to one day take over the power of Sweden as an absolute king, an absolute power which Charles XI himself introduced to the realm through the Riksdags of 1680 and 1682 and which was based on the theory of kingship by the grace of God.

Training

When Charles was four years old, he was assigned his first teacher, Andreas Nordenhielm, rector and professor of practical philosophy at Uppsala University. For eight years, Nordenhielm taught the young prince reading and writing exercises as well as language, history and moral issues. In May 1687, the prince wrote his first sentence, "After God's kingdom we should first seek, then everything else will fall to us", and as a six-year-old he wrote his first letters. At the same age, Charles XI took direct command of his son's upbringing, appointing the court chancellor Erik Lindschöld and later the royal council Nils Gyldenstolpe as his son's governors, but neither became a favorite of the prince as Nordenhielm had become. The state secretary Tomas Polus and the chamberlain Gustaf Cronhielm also came to participate in the prince's teaching. On 2 January 1689, the prince was moved to his own floor in the castle with his own court, staff of servants and regiment.

In 1690, Charles XI issued new teaching instructions, which were to be followed to the letter until the prince's eighteenth birthday in preparation for his eventual assumption of power. A guiding thought behind the prince's upbringing was tabula rasa, Aristotle's educational theory about the infinitely malleable child, where the prince should be surrounded by wise and virtuous men in order to grow up to be a wise and virtuous prince. The prince was taught Christianity and theology, which was in charge of the bishop of Strängnäs Erik Benzelius, teaching in leading cultural languages as well as ancient history, mainly the campaigns of Alexander the Great and Julius Caesar through works written by Cornelius Nepos, Titus Livius, Phaedrus, Marcus Junianus Justinus and Quintus Curtius Rufus . From their works Charles could recite long quotations by heart, several of which he used in correspondence with his servants and foreign diplomats. The prince's favorite author was Rufus and later in life he came to carry with him a small pocket edition of Rufus's biography of Alexander the Great, whom the prince saw as his great idol.

Charles gained knowledge of general history both through the Latin lessons and from the works of Laurentius Petris and Samuel von Pufendorf, where the prince was fascinated by the person and life fate of Gustav II Adolf. The prince learned mathematics and military science from Lieutenant General Quartermaster Carl Magnus Stuart, who taught the prince mathematical solutions to tactical problems, as well as Erik Dahlbergh's topographical engravings and depictions of the battles of Charles X Gustav and Charles XI. When the prince's education was later interrupted when he was fifteen years old, he did not get any deeper knowledge of philosophy, political science and the history of war from a strategic point of view. The prince early showed a particular interest and talent for mathematics and the art of fortification.

Karl XI also came to leave a mark on the prince's tough and powerful masculine ideals; the latter increasingly began to imitate his father's mannerisms and habits. Early on, Karl began to participate in his father's exercise and inspection trips, as well as in hunting parties from the age of seven. Both he and his father rode long distances together, usually with record hunting in mind. When the prince was twelve years old, he and his father rode from Södertälje to Stockholm for two and a half hours, and some time later they rode between Uppsala and Ulriksdal castle in just under four hours.

In his young years, Karl was described as knowledgeable, talented and diligent, who assimilated his teaching very well. He acquired excellent knowledge of Swedish and spoke German and Latin fluently. He had learned French by reading about the life of the French king Henry IV and the dramas of Corneille, Molière and Racine, but over time he avoided speaking French. Later in life, he also learned to speak a little Finnish, Italian, Polish, Turkish and Greek. He also became a good fencer, an excellent horseman and could skillfully handle firearms.

Early campaigns

Around 1700, the monarchs of Denmark–Norway, Saxony (ruled by elector August II of Poland, who was also the king of Poland-Lithuania) and Russia united in an alliance against Sweden, mainly through the efforts of Johann Reinhold Patkul, a Livonian nobleman who turned traitor when the "great reduction" of Charles XI in 1680 stripped much of the nobility of lands and properties. In late 1699, Charles sent a minor detachment to reinforce his brother-in-law Duke Frederick IV of Holstein-Gottorp, who was attacked by Danish forces the following year. A Saxon army simultaneously invaded Swedish Livonia, and in February 1700 surrounded Riga, the most populous city of the Swedish Empire. Russia also declared war (August 1700), but stopped short of an attack on Swedish Ingria until September 1700.

Charles's first campaign was against Denmark–Norway, ruled by his cousin Frederick IV of Denmark. For this campaign Charles secured the support of England and the Netherlands, both maritime powers concerned with Denmark's threats too close to the Sound. Leading a force of 8,000 and 43 ships in an invasion of Zealand, Charles rapidly compelled the Danes to submit to the Peace of Travendal in August 1700, which indemnified Holstein. Having forced Denmark–Norway to make peace within months, King Charles turned his attention upon the two other powerful neighbors, King August II (cousin to both Charles XII and Frederick IV of Denmark–Norway) and Peter the Great of Russia, who also had entered the war against him, ironically on the same day that Denmark came to terms.

Russia had opened their part of the war by invading the Swedish-held territories of Livonia and Estonia. Charles countered this by attacking the Russian besiegers at the Battle of Narva (November 1700). The Russians outnumbered the Swedish army of ten thousand men by almost four to one. Charles attacked under cover of a blizzard, effectively splitting the Russian army in two and won the battle. Many of Peter's troops who fled the battlefield drowned in the Narva River. The total number of Russian fatalities reached about 10,000 at the end of the battle, while the Swedish forces lost 667 men.

Charles did not pursue the Russian army. Instead, he turned against Poland-Lithuania, which was formally neutral at this point, thereby disregarding Polish negotiation proposals supported by the Swedish parliament. Charles defeated the Polish king Augustus II and his Saxon allies at the Battle of Kliszow in 1702 and captured many cities of the Commonwealth. After the deposition of Augustus as king of the Polish–Lithuanian Commonwealth, Charles XII put Stanisław Leszczyński as his puppet on the Polish throne (1704).

Headquarters in Altranstädt

The Swedish army was stationed in Saxony for a year and, according to the provisions of the Altranstädt Treaty, significant war taxes were taken from the Saxon estates for its maintenance. The long break was used by Charles XII to re-equip his army, call in recruits from Sweden and set up new regiments through enlistments in Germany. In Günthersdorf on December 7, 1706, Charles XII had his first meeting with August II, which according to his historiographer Gustaf Adlerfelt was done in a polite way: "both kings embraced and temoigned (showed) each other much friendship". He showed courtesy by inviting him and letting him sit by his side at royal tables in Altranstädt. The courtesies ended, however, when Charles XII got hold of August II's secret correspondence with Tsar Peter I, in which the latter promised to preserve his alliance with Russia. Charles XII forced him to once again certify the peace and tightened the already harsh contribution requirements.

Meanwhile in Saxony, Charles XII's headquarters were transformed into a center for parties, balls, theater performances and hospitality, as well as one of the focal points of European politics. Several princes, diplomats, soldiers, noble ladies and fortune seekers from all over Europe gathered in Altranstädt to meet the victorious king in person. However, most had to settle for a glimpse of him when he held an open table in front of a large audience in the Altranstädt castle's great dining room. Several of the spectators were astonished by the king's different appearance, demeanor and table manners. According to the English ambassador in Berlin, Thomas Wentworth, Charles XII was "tall and stately but exceedingly dirty and unkempt. His behavior is more uncouth than one would expect from so young a man." In a letter to professor Johan Upmarck Rosenadler, the Uppsala student Anders Alstrin described that the king "seems so strange to me, so singular and incomprehensible because in everything he does, in all his actions and expressions, so that I can say nothing, however, he is so gracious and gets on so well with everybody. No likeness of all the ones I've seen is quite like him." According to the writer Bengt Liljegren, Charles XII was not unaware of the attention surrounding him, but that he did not seem to attach much to it.

When the War of the Spanish Succession was still going on, several rulers in Europe were interested in Charles XII's future war movements and which side he would choose in the conflict. The hope of the anti-French alliance was that Charles XII would leave Saxony as soon as possible and turn towards Russia, as the presence of the Swedes on Austria's northern border weakened the imperial troops' ability to conquer France. For this purpose, at the end of April 1707, Queen Anna of Great Britain sent her special envoy to the Swedish headquarters, the infamous English general John Churchill, Duke of Marlborough. The meeting between Marlborough and Charles XII was not very cordial, but to the Duke's great relief the King announced that he was maintaining his line of neutrality in the War of Succession.

At the same time, a conflict flared up between Charles XII and Emperor Joseph I, where the latter, according to the provisions of the Peace of Westphalia, was supposed to guarantee religious freedom for the Protestant population of Silesia, something that they had not received in reality. With the emperor's good memory, several Lutheran churches in the province had instead been closed down by the Catholics. Coupled with some military incidents affecting Swedish soldiers in Silesia, Charles XII threatened to occupy the entire province to reach a settlement. He pressed the emperor further by entering into negotiations with King Frederick I of Prussia for an evangelical triple alliance with Hanover as the third party. With assistance from Great Britain and the Netherlands, Austria was forced to give in and the dispute was resolved by the Altranstädt Convention, which was signed on August 22, 1707. Through the treaty, the Protestants in Silesia regained their freedom of religion and a number of churches, schools and hospitals previously taken over by the Catholics were returned to the Lutherans. Although the evangelical triple alliance never came to fruition, Charles XII through his negotiations had secured the backing of both Saxony and Prussia for his Russian campaign.

Russian resurgence

While Charles won several decisive battles in the Commonwealth and ultimately secured the coronation of his ally Stanisław Leszczyński and the surrender of Saxony, the Russian Tsar Peter the Great embarked on a military reform plan that improved the Russian army, using the effectively organized Swedes and other European armies as role models. Russian forces managed to penetrate Ingria, where they established a new city, Saint Petersburg. Charles planned an invasion of the Russian heartland, allying himself with Ivan Mazepa, Hetman of the Ukrainian Cossacks. The size of the invading Swedish army was peeled off as Charles left Leszczyński with some 24,000 German and Polish troops, departing eastwards from Saxony in late 1707 with some 35,000 men, adding a further 12,500 under Adam Ludwig Lewenhaupt marching from Livonia. Charles left the homeland with a defense force of approximately 28,800 men, with a further 14,000 in Swedish Finland, as well as other garrisons in the Baltic and German provinces.

After securing his "favorite" victory in the Battle of Holowczyn, despite being outnumbered over three to one by the new Russian army, Charles opted to march eastwards on Moscow rather than try to seize Saint Petersburg, founded from the Swedish town of Nyenskans five years earlier. Peter the Great managed, however, to ambush Lewenhaupt's army at Lesnaya before Charles could combine his forces, thus losing valuable supplies, artillery and half of Lewenhaupt's men. Charles' Polish ally, Stanisław Leszczyński, was facing internal problems of his own. Charles expected the support of a massive Cossack rebellion led by Mazepa in Ukraine, with estimates suggesting Mazepa was able to muster about 40,000 troops. However, the Russians subjugated the rebellion and destroyed its capital, Baturin, before the arrival of the Swedish troops. The harsh climate took its toll as well, because Charles marched his troops to winter camp in Ukraine.

By the time of the decisive Battle of Poltava, in July 1709, Charles had been wounded, one-third of his infantry was dead, and his supply train had been destroyed. The king was incapacitated by a gunshot wound to the foot and was unable to lead the Swedish forces. With the numbers of Charles' army reduced to some 23,000, with many wounded or involved on the siege of Poltava, his general Carl Gustav Rehnskiöld had a clearly inferior force to face the fortified and modernized army of Tsar Peter, with some 45,000 men. The Swedish assault ended in disaster, and the king fled south to the Ottoman Empire with a small entourage, and set up camp at Bender with some 1,000 of his Caroleans ("Karoliner" in Swedish). The remainder of the army surrendered days later at Perevolochna under Lewenhaupt's command, most of them (including Lewenhaupt himself) spending the rest of their days in Russian captivity.

The Swedish defeat at Poltava marked the downfall of the Swedish Empire,  as well as the founding of the Russian Empire.

Exile in the Ottoman Empire

The Ottomans initially welcomed the Swedish king, where he went to Abdurrahman Pasha, the commander of Özü Castle, as he was about to fall into the hands of the Russian army, and he was able to take refuge in the castle at the last moment. Afterward, he settled in Bender at the invitation of its governor, Ağa Yusuf Pasha.

In the meantime, Charles sent Stanisław Poniatowski and Thomas Funck  as his messengers to Constantinople. They managed to indirectly contact with Gülnuş Sultan, mother of Sultan Ahmed III, who became intrigued by Charles, in which she took an interest in his cause, and even corresponded with him in Bender.

His expenses during his long stay in the Ottoman Empire were covered by the Ottoman state budget, as part of the fixed assets (Demirbaş in Turkish), hence his nickname Demirbaş Şarl (Fixed Asset Charles) in Turkey.

Eventually, a small village named Karlstad (Varnița) had to be built near Bender to accommodate the ever-growing Swedish population there.

Gülnuş Sultan convinced her son to declare war against Russia, as she thought that Charles was a man worth taking a risk for. Later on, the Ottomans and Russians signed the Treaty of the Pruth and Treaty of Adrianople to end the hostilities between them. The treaties dissatisfied the pro-war party, supported by King Charles and Stanislaw Poniatowski who failed to reignite the conflict.

However, the Sultan Ahmed III's subjects in the empire eventually got tired of Charles' scheming. His entourage also accumulated huge amounts of debts with Bender merchants. Eventually, "crowds" of townspeople attacked the Swedish colony at Bender and Charles had to defend himself against the mobs and the Ottoman Janissaries involved. This uprising was called "kalabalık" (Turkish for crowd) which afterward found a place in Swedish lexicon referring to a ruckus. The Janissaries did not shoot Charles during the skirmish at Bender, but captured him and put him under house-arrest at Dimetoka (nowadays Didimoticho) and Constantinople. During his semi-imprisonment the King played chess and studied the Ottoman Navy and the naval architecture of the Ottoman galleons. His sketches and designs eventually led to the famous Swedish war ships Jarramas (Yaramaz) and Jilderim (Yıldırım).

Meanwhile, Russia and Poland regained and expanded their borders. Great Britain, an adversary of Sweden, defected from its alliance obligations while Prussia attacked Swedish holdings in Germany. Russia occupied Finland (the Greater Wrath 1713–1721). After defeats of the Swedish army, consisting mainly of Finnish troops in the Battle of Helsinki (1713), the Battle of Pälkäne 1713 and the Battle of Storkyro 1714, the military, administration and clergymen escaped from Finland, which fell under Russian military regime.

During his five-year stay in the Ottoman Empire, Charles XII corresponded with his sister (and eventual successor), Ulrika Eleonora. According to Mrs. Ragnhild Marie Hatton, a Norwegian-British historian, in some of those letters Charles expressed his desire for a peace treaty which would be defensible in the future Swedish generations' eyes. However, he emphasized that only a greater respect for Sweden in Europe would enable him to achieve such a peace treaty. Meanwhile, the Swedish Council of State (government) and Estates/Diet (Parliament) tried to keep the beleaguered Sweden somehow organized and independent. Eventually, in the autumn of 1714, their warning letter reached him. In it, those executive and legislative bodies told the absentee King that unless he quickly returned to Sweden, they would independently conclude an achievable peace treaty with Russia, Poland and Denmark. This stark admonition prompted Charles to rush back to Sweden.

Charles traveled back to Sweden with a group of Ottomans, soldiers such as escorts and businessmen to whom he promised to repay his debts during his stay in the Ottoman Empire, but they had to wait several years before that happened. According to the prevailing church law in Sweden at that time, all who lived in the country, but were not members of the Swedish state church, would be baptized. In order for the Jewish and Muslim creditors to avoid this, Charles wrote a "free letter" so that they could practice their religions without being punished. The soldiers chose to remain in Sweden instead of difficult trips home. They were called "Askersson" (the word asker in Turkish means soldier). However, there are accounts implying that following the long stay for Charles to repay his debts, they got paid and left the country.

Pomerania and Norway

Charles agreed to leave Constantinople and returned to Swedish Pomerania. He made the journey on horseback, riding across Europe in just fifteen days. He traveled across the Habsburg Kingdom of Hungary to Vienna and arrived at Stralsund. A medal with Charles on horseback, his long hair flying in the wind, was struck in 1714 to commemorate the speedy ride. It reads Was sorget Ihr doch? Gott und Ich leben noch. (What worries you so? God and I live still.).

After five years away, Charles arrived in Sweden to find his homeland at war with Russia, Saxony, Hannover, Great Britain and Denmark. Sweden's western enemies attacked southern and western Sweden while Russian forces traveled across Finland to attack the Stockholm district. For the first time, Sweden found itself in a defensive war. Charles' plan was to attack Denmark by striking at her possessions in Norway. It was hoped that by cutting Denmark's Norwegian supply lines the Danes would be compelled to withdraw their forces from Swedish Scania.

Charles invaded Norway in 1716 with a combined force of 7,000 men. He occupied the capital of Christiania, (modern Oslo), and laid siege to the Akershus fortress there. Due to a lack of heavy siege cannons he was unable to dislodge the Norwegian forces inside. After suffering significant losses of men and materiel, Charles was forced to retreat from the capital on 29 April. In the following mid-May, Charles invaded again, this time striking the border town of Fredrikshald, now Halden, in an attempt to capture the fortress of Fredriksten. The attacking Swedes came under heavy cannon fire from the fortress and were forced to withdraw when the Norwegians set the town of Fredrikshald on fire. Swedish casualties in Fredrikshald were estimated at 500 men. While the siege at Fredrikshald was underway, the Swedish supply fleet was attacked and defeated by Tordenskjold in the Battle of Dynekilen.

In 1718, Charles once more invaded Norway. With a main force of 40,000 men, he again laid siege to the fortress of Fredriksten overlooking the town of Fredrikshald. Charles was shot in the head and killed during the siege, while he was inspecting trenches. The invasion was abandoned, and Charles' body was returned to Sweden. A second force, under Carl Gustaf Armfeldt, marched against Trondheim with 10,000 men but was forced to retreat. In the march that ensued, many of the 5,800 remaining men perished in a severe winter storm.

Death

While in the trenches close to the perimeter of the fortress on 30 November (11 December New Style), 1718, Charles was struck in the head by a projectile and killed. The shot struck the left side of his skull and exited from the right. He died instantly.

The definitive circumstances around Charles's death remain unclear. Despite multiple investigations of the battlefield, Charles's skull and his clothes, it is not known where and when he was hit, or whether the shot came from the ranks of the enemy or from his own men. There are several hypotheses as to how Charles died, though none have strong enough evidence to be deemed true. Although there were many people around the king at the time of his death, there were no known witnesses to the actual moment he was hit. A likely explanation has been that Charles was killed by Dano-Norwegians as he was within reach of their guns. There are two possibilities that are usually cited: that he was killed by a musket shot, or that he was killed by grapeshot from the nearby fortress.

More theories claim he was assassinated: one is that the killer was a Swedish compatriot and asserts that enemy guns were not firing at the time Charles was struck. Suspects in this claim range from a nearby soldier tired of the siege and wanting to put an end to the war, to an assassin hired by Charles's own brother-in-law, who profited from the event by subsequently taking the throne himself as Frederick I of Sweden, that person being Frederick's aide-de-camp, André Sicre. Sicre confessed during what was claimed to be a state of delirium brought on by fever but later recanted. It has also been suspected that a plot to kill Charles may have been put in place by a group of wealthy Swedes who would benefit from the blocking of a 17% wealth tax that Charles intended to introduce. In the Varberg Fortress museum there is a display with a lead-filled brass button of Swedish origin that is claimed by some to be the projectile that killed the king.

Another odd account of Charles's death comes from Finnish writer Carl Nordling, who states that the king's surgeon, Melchior Neumann, dreamed the king had told him that he was not shot from the fortress but from "one who came creeping".

Charles's body has been exhumed on three occasions to ascertain the cause of death; in 1746, 1859 and 1917. The 1859 exhumation found that the wound was in accordance with a shot from the Norwegian fort. In 1917, his head was photographed and x-rayed. Peter Englund asserted in his essay "On the death of Charles XII and other murders" that the mortal wound sustained by the King, with a smaller exit wound than entry wound, would be consistent with being hit by a bullet with a speed not exceeding 150 m/s, concluding that Charles was killed by stray grapeshot from the nearby fortress. A 2022 study also found that iron grapeshot was likely to have killed the king, citing evidence from ballistic experiments as well as the absence of lead fragments in Charles's skull.

Academic research from University of Oulu and University of Helsinki concluded that Charles XII was likely killed by an enemy projectile.

Charles was succeeded to the Swedish throne by his sister, Ulrika Eleonora. As his duchy of Palatine Zweibrücken required a male heir, Charles was succeeded as ruler there by his cousin Gustav Leopold. Georg Heinrich von Görtz, Charles' minister, was beheaded in 1719.

Personal life

Charles never married and fathered no children of whom historians are aware. In his youth, he was particularly encouraged to find a suitable spouse in order to secure the succession, but he would frequently avoid the subject of sex and marriage. Possible candidates included Princess Sophia Hedwig of Denmark, Louisa Maria Stuart and Princess Maria Elisabeth of Holstein-Gottorp – but of the latter he pleaded that he could never wed someone "as ugly as Satan and with such a devilish big mouth". Instead, he made it clear that he would marry only someone of his own choice, and for love rather than dynastic pressures. His lack of mistresses may have been due to a strong religious faith. Charles himself suggested in conversation with Axel Löwen that he actively resisted any match until peace could be secured and was in some sense "married" to the military life. But that he was "chaste" occasioned speculation in his lifetime. Much later speculation that he was a hermaphrodite was quelled in 1917 when his coffin was opened and he was shown to have beard growth.

In his conversations with Löwen, he also stated that he did not lack taste for beautiful women, but that he held in his sexual desires for fear that they would get out of control if unchecked, and that if he committed to something like that, it would be forever. Some historians suggest that he resisted a marriage with Denmark which could have caused a family rift between those who dynastically favoured Holstein-Gottorp. Historians such as Blanning and Montefiore believe he was in fact homosexual. Certainly a letter from Reuterholm suggested that Charles had indicated a closeness to the Elector Prince of Saxony, Maximilian Emanuel of Württemberg-Winnental, whom Charles described as "very pretty". But writing in the 1960s, Hatton argues that Württemberg was very much heterosexual and the relationship is just as likely to have been that of teacher-pupil.

Legacy

Exceptional for abstaining from alcohol and sex, he felt most comfortable during warfare. Contemporaries report of his seemingly inhuman tolerance for pain and his utter lack of emotion. His brilliant campaigning and startling victories brought his country to the pinnacle of her prestige and power, although the Great Northern War resulted in Sweden's defeat and the end of the empire within years of his own death. In his youth, renowned Russian general Alexander Suvorov considered Charles XII his hero together with Julius Caesar. Like Charles XII, Suvorov adopted an aggressive style of tactics and campaigning, seemingly inspired by the Swedish king.

Charles's death marked the end of autocratic kingship in Sweden, and the subsequent Age of Liberty saw a shift of power from the monarch to the parliament of the estates. Historians of the late 18th and early 19th centuries viewed Charles' death as the result of an aristocratic plot, and Gustav IV Adolf, the king who refused to settle with Napoleon Bonaparte, "identified himself with Charles as a type of righteous man struggling with iniquity " (Roberts). Throughout the 19th century's romantic nationalism Charles XII was viewed as a national hero. He was idealized as a heroic, virtuous young warrior king, and his fight against Peter the Great was associated with the contemporary Swedish-Russian enmity. Examples of the romantic hero idolatry of Charles XII in several genres are Esaias Tegnér's song Kung Karl, den unge hälte (1818), Johan Peter Molin's statue in Stockholm's Kungsträdgården (unveiled on 30 November 1868, the 150th anniversary of Charles's death) and Gustaf Cederström's painting Karl XII's funeral procession ("Funeral procession of Charles XII", 1878). The date of Charles's death was chosen by a student association in Lund for annual torch marches beginning in 1853.

In his 1901 play Karl XII, August Strindberg broke with the heroization practice by showing an introverted Charles XII in conflict with his impoverished subjects. In the so-called Strindberg feud (1910–1912), his response to the "Swedish cult of Charles XII" (Steene) was that Charles had been "Sweden's ruin, the great offender, a ruffian, the rowdies' idol, a counterfeiter ." Verner von Heidenstam however, one of his opponents in the feud, in his book Karolinerna instead "emphasized the heroic steadfastness of the Swedish people in the somber years of trial during the long-drawn-out campaigns of Karl XII" (Scott).

In the 1930s, the Swedish National Socialists held celebrations on the date of Charles XII's death, and shortly before the outbreak of World War II, Adolf Hitler received from Sweden a sculpture of the king on his birthday. In the late 20th century, Swedish nationalists and 'neo-Nazis' had again used 30 November as a date for their ceremonies, however these were regularly interrupted by larger counter-demonstrations and were abandoned.

Scientific contributions

Apart from being a monarch, the King's interests included mathematics, and anything that would be beneficial to his warlike purposes. He is credited with having invented an octal numeral system, as well as a more elaborate one with the base 64, which he considered more suitable for war purposes because all the boxes used for materials such as gunpowder were cubic. According to a report by contemporary scientist Emanuel Swedenborg, the King had sketched a model of his thoughts on a piece of paper and handed it to him at their meeting in Lund in 1716. The paper was reportedly still in existence a hundred years later but has since been lost.