Sons of kings

Wilhelm, German Crown Prince, Crown Prince of Prussia (Friedrich Wilhelm Victor August Ernst; 6 May 1882 – 20 July 1951) was the eldest child of the last Kaiser, Wilhelm II, German Emperor, and his consort Augusta Victoria of Schleswig-Holstein, and thus a great-grandson of Queen Victoria, and distant cousin to many British Royals, such as Queen Elizabeth II. As Emperor Wilhelm's heir, he was the last Crown Prince of the German Empire and the Kingdom of Prussia, until the abolition of the monarchy.
Wilhelm became crown prince at the age of six in 1888, when his grandfather Frederick III died and his father became emperor. He was crown prince for 30 years until the fall of the empire on 9 November 1918. During World War I, he commanded the 5th Army from 1914 to 1916 and was commander of the Army Group German Crown Prince for the remainder of the war. After his return to Germany in 1923, he fought the Weimar Republic and campaigned for the reintroduction of the monarchy in Germany. After his plans to become president had been blocked by his father, Wilhelm supported Adolf Hitler's rise to power, but when Wilhelm realised that Hitler had no intention of restoring the monarchy, their relationship cooled. Wilhelm became head of the House of Hohenzollern on 4 June 1941 following the death of his father and held the position until his own death on 20 July 1951.

Philip III (1 May 1245 – 5 October 1285), called the Bold (French: le Hardi), was King of France from 1270 until his death in 1285. His father, Louis IX, died in Tunis during the Eighth Crusade. Philip, who was accompanying him, returned to France and was anointed king at Reims in 1271.
Philip inherited numerous territorial lands during his reign, the most notable being the County of Toulouse, which was annexed to the royal domain in 1271. With the Treaty of Orléans, he expanded French influence into the Kingdom of Navarre and following the death of his brother Peter during the Sicilian Vespers, the County of Alençon was returned to the crown lands.
Following the Sicilian Vespers, Philip led the Aragonese Crusade in support of his uncle. Initially successful, Philip, his army racked with sickness, was forced to retreat and died from dysentery in Perpignan in 1285 at the age of 40. He was succeeded by his son Philip IV.

Oscar II (Oscar Fredrik; 21 January 1829 – 8 December 1907) was King of Sweden from 1872 until his death in 1907 and King of Norway from 1872 to 1905.
Oscar was the son of King Oscar I and Queen Josephine. He inherited the Swedish and Norwegian thrones when his brother died in 1872. Oscar II ruled during a time when both countries were undergoing a period of industrialization and rapid technological progress. His reign also saw the gradual decline of the Union of Sweden and Norway, which culminated in its dissolution in 1905. In 1905, the throne of Norway was transferred to his grandnephew Prince Carl of Denmark under the regnal name Haakon VII. When Oscar died in 1907, he was succeeded in Sweden by his eldest son, Gustaf V.
Oscar II is the paternal great-great-grandfather of King Carl XVI Gustaf of Sweden. King Frederik X of Denmark is Oscar II's descendant through his son Gustaf V. King Harald V of Norway; King Philippe of the Belgians; and Henri, Grand Duke of Luxembourg are also descendants of Oscar II, all through his third son Prince Carl, Duke of Västergötland.

Gustavus Adolphus (9 December [N.S 19 December] 1594 – 6 November [N.S 16 November] 1632), also known in English as Gustav II Adolf or Gustav II Adolph, was King of Sweden from 1611 to 1632, and is credited with the rise of Sweden as a great European power (Swedish: Stormaktstiden). During his reign, Sweden became one of the primary military forces in Europe during the Thirty Years' War, helping to determine the political and religious balance of power in Europe. He was formally and posthumously given the name Gustavus Adolphus the Great (Swedish: Gustav Adolf den store; Latin: Gustavus Adolphus Magnus) by the Riksdag of the Estates in 1634.He is often regarded as one of the greatest military commanders in modern history, with use of an early form of combined arms. His most notable military victory was the Battle of Breitenfeld in 1631. With his resources, logistics, and support, Gustavus Adolphus was positioned to become a major European leader, but he was killed a year later at the Battle of Lützen. He was assisted in his efforts by Count Axel Oxenstierna, the Lord High Chancellor of Sweden, who also acted as regent after his death.
Coming to the throne at the age of 16, Gustavus Adolphus inherited three wars from his father Charles IX of Sweden: border conflicts with Russia and Denmark–Norway, and a dynastic struggle with his first cousin, King Sigismund III Vasa of Poland. Of these, the Danish war was the most serious. During his reign, Sweden rose from the status of a Baltic Sea basin regional power to one of the great powers of Europe and a model of early modern era government. Gustavus Adolphus is known as the "father of modern warfare", or the first modern general. He taught a number of other military commanders, such as Lennart Torstensson, who would go on to expand the boundaries and power of the Swedish Empire after Gustavus Adolphus's death. Spoils meant he became a successful bookraider in Europe, targeting Jesuit collections.His contributions to Sweden's rise in power included reformation of the administrative structure. For example, he began Parish Registration of the population, so that the central government could more efficiently tax and conscript the people. He is also widely commemorated by Protestants in Europe as the main defender of their cause during the Thirty Years' War, with multiple churches, foundations and other undertakings named after him, including the Gustav-Adolf-Werk.

Prince Alexandre of Belgium (French: Alexandre Emmanuel Henri Albert Marie Léopold, Dutch: Alexander Emanuel Hendrik Albert Maria Leopold; 18 July 1942 – 29 November 2009) was the fourth child of King Leopold III of Belgium, and the eldest for Lilian, Princess of Réthy. King Baudouin and King Albert II of Belgium were his older half-brothers. Grand Duchess Joséphine-Charlotte of Luxembourg was his older half-sister.

Charles Léon Denuelle de la Plaigne, Count Léon (13 December 1806 – 14 April 1881) was an illegitimate son of Emperor Napoleon of France and Napoleon's mistress Louise Catherine Eléonore Denuelle de la Plaigne. Brought up in France, Léon began a military career in Saint-Denis where he was head of a battalion of the national guard.
Admirative of his father, he tried to keep the memory of the First Empire alive by organizing several commemorations. After the fall of his cousin Napoleon III and of the Second Empire, Léon retired in Pontoise, France, and died in poverty.

Jérôme Napoléon "Bo" Bonaparte (5 July 1805 – 17 June 1870) was an American farmer, chairman of the Maryland Agricultural Society, first president of the Maryland Club, and the son of Elizabeth Patterson and Jérôme Bonaparte, brother of Napoleon I.

Edgar Stuart, Duke of Cambridge (14 September 1667 – 8 June 1671) was the fourth son of James, Duke of York (later James II of England) and his first wife Anne Hyde. He was second in the line of succession to the English and Scottish thrones.

Charles Stuart, Duke of Kendal (4 July 1666 – 22 May 1667) was the third son of James, Duke of York (later James II of England) and his first wife Anne Hyde.
Charles was born on 4 July 1666 at St James's Palace. His godparents were his three-year-old brother James, Duke of Cambridge, his cousin James, Duke of Monmouth, and Emilia von Nassau, Countess of Ossory. He was designated Duke of Kendal and was to have been created Duke of Kendal, Earl of Wigmore, and Baron of Holdenby, but no patent was ever enrolled. He died at St James's Palace at the age of 10 months on 22 May 1667 and was buried in Westminster Abbey on 30 May 1667.

Monsieur d'Orléans (16 April 1607 – 17 November 1611) was the second son and fourth child of Henry IV of France and his consort, Marie de' Medici. Commonly ascribed the names Nicolas or Nicolas Henri and the title Duke of Orléans, he was neither baptised nor invested as such during the course of his short life.
He was betrothed to Marie de Bourbon-Montpensier, heiress to vast lands of the extended House of Bourbon. After his father's death in 1610, he was heir presumptive to his older brother, Louis XIII. Of frail health, he died of seizures brought on by hydrocephalus at the age of four, whereupon his title and betrothal were transferred to Gaston, his younger brother.