Alexander I Karađorđević (Serbo-Croatian: Александар I Карађорђевић, Aleksandar I Karađorđević, 16 December [O.S. 4 December] 1888 – 9 October 1934) was King of the Serbs, Croats and Slovenes from 16 August 1921 to 3 October 1929 and King of Yugoslavia from 3 October 1929 until his assassination. His thirteen-year reign was the longest of the kingdom's three monarchs. He served as the de facto head of state of the Kingdom of Serbia from 1914 to 1918 and of Yugoslavia from 1918 to 1921 as prince regent for his father, Peter I.
Born in Cetinje, Montenegro, Alexander was the second son and fourth child of Peter and Zorka Karađorđević. The House of Karađorđević had been deposed in Serbia 30 years earlier by the rival House of Obrenović, and Alexander spent his early life in exile with his father in Montenegro and later Switzerland. He subsequently moved to the Russian Empire and enrolled in the imperial Page Corps. Following the May Coup and the assassination of King Alexander I Obrenović in 1903, Peter ascended the Serbian throne. In 1909, Alexander's elder brother, Prince George, renounced his succession rights, making Alexander heir apparent. Alexander distinguished himself as a field commander during the Balkan Wars, leading Serbian forces to victories over the Ottoman Empire and the Bulgarians. In 1914, he was appointed prince regent after his father transferred his royal duties due to ill health. During the First World War, he held nominal supreme command of the Royal Serbian Army.
In 1918, Alexander oversaw the unification of Serbia and the former Austro-Hungarian provinces of Croatia-Slavonia, Slovenia, Vojvodina, Bosnia and Herzegovina, and Dalmatia into the Kingdom of Serbs, Croats and Slovenes, in accordance with the Corfu Declaration. He subsequently became known as Alexander the Unifier. Alexander continued as prince regent and de facto head of state until ascending the throne upon his father's death in 1921. An extended political crisis followed, culminating in the assassination of Croat political leader Stjepan Radić. In response, Alexander abolished the Vidovdan Constitution in 1929, prorogued parliament, renamed the state the Kingdom of Yugoslavia, and instituted a royal dictatorship. The 1931 Constitution formalised his personal rule and established Yugoslavia as a unitary state, increasing resentment among the non-Serb population. Domestic tensions were further exacerbated by the onset of the Great Depression, which severely affected the country's agrarian economy. In foreign policy, Alexander promoted the Balkan Pact with Greece, Romania, and Turkey, and sought closer relations with Bulgaria.
In October 1934, Alexander made an official visit to the French Republic to consolidate support for the Little Entente against Hungarian revanchism and Italian expansionism. While travelling through Marseille, he was assassinated by Vlado Chernozemski, an operative of the Internal Macedonian Revolutionary Organization acting with support from the Ustaše, led by Ante Pavelić. French Foreign Minister Louis Barthou was also killed in the attack. Alexander was succeeded by his eleven-year-old son, Peter II, under a regency council headed by his cousin Prince Paul.
Alexander Karađorđević was born on 16 December 1888 [O.S. 4 December] in the Principality of Montenegro as the fourth child and second son of Peter Karađorđević and his wife, Princess Zorka of Montenegro. His paternal grandfather, also named Alexander, had been forced to abdicate as prince of Serbia and surrender power to the rival House of Obrenović. Alexander's maternal grandfather was Nicholas I, Prince of Montenegro. Despite enjoying support from the Russian Empire, at the time of Alexander's birth and early childhood, the House of Karađorđević was in political exile, with family members scattered all over Europe, unable to return to Serbia due to their rivalry with the House of Obrenović.
Serbia had recently been transformed from a principality into a kingdom under the Obrenovićes, who ruled with strong support from the Austro-Hungarian Empire. The antagonism between the two rival royal houses was such that, after the assassination of Prince Mihailo Obrenović in 1868 (an event in which the Karađorđevićes were suspected of taking part), the Obrenovićes made constitutional changes banning the Karađorđevićes from entering Serbia and stripping them of their civic rights.
Alexander was two when his mother, Princess Zorka, died in 1890 from complications while giving birth to his younger brother, Andrej, who died 23 days later. Alexander spent his childhood in Montenegro. In 1894, his widowed father took the four children, including Alexander, to Geneva, Switzerland, where he completed his elementary education. Alongside his older brother George, he continued his schooling at the imperial Page Corps in Petrograd, Russian Empire. The British historian Robert Seton-Watson described Alexander as becoming a Russophile during his time in Petrograd, feeling deep gratitude for the willingness of the Russian emperor Nicholas II to grant him refuge, where he was treated with great honour and respect.
As a page, Alexander was described as hard-working and determined while also being a "loner" who kept to himself and rarely showed his feelings. Nicholas II invited Alexander to dinners at the Winter Palace, where he was the guest of honour at meals hosted by the Russian imperial family, which was a great privilege for a prince from Serbia's deposed royal family. During his time in Petrograd, Alexander visited the Alexander Nevsky Monastery, where the abbot gave him an icon of Prince Alexander Nevsky and guided him to the grave of Marshal Alexander Suvorov. After his visit to the monastery, Alexander expressed the wish to be a great general like Marshal Suvorov or Prince Alexander Nevsky, saying he wanted to command either a great army or a great armada when he was a man.
In 1903, while young George and Alexander were in school, a group of conspirators carried out a bloody coup d'état in the Kingdom of Serbia, in which King Alexander and Queen Draga were murdered and dismembered. The House of Karađorđević thus retook the Serbian throne after 45 years, and Alexander's 58-year-old father became King of Serbia, prompting George and Alexander to return to Serbia to continue their studies. After Alexander's 15th birthday, King Peter had him enlisted in the Royal Serbian Army as a private, with instructions to his officers to promote his son only if he proved worthy. On 25 March 1909, Alexander was suddenly recalled to Belgrade by his father with no explanation offered other than that he had an important announcement for his son.
In 1909, a scandal broke when Crown Prince George, Alexander's older brother, killed a servant by kicking him in the stomach. Following pressure from powerful figures such as Prime Minister Nikola Pašić and high-ranking officers Dragutin "Apis" Dimitrijević and Petar Živković, George publicly renounced his claim to the throne in March of that year in favour of Alexander.
In 1910, Alexander nearly died from stomach typhus and was left with stomach problems for the rest of his life. In the run-up to the First Balkan War, Alexander played the role of a diplomat, visiting Sofia to meet Tsar Ferdinand I of Bulgaria for secret talks on forming a Balkan League to drive the Ottoman Turks out of the Balkans. Both Bulgaria and Serbia had rival claims to the Ottoman region of Macedonia, so Alexander, along with Ferdinand's son Crown Prince Boris, travelled to Petrograd to meet with Emperor Nicholas II and request Russian mediation. In March 1912, Serbia and Bulgaria signed a defensive alliance, which Greece joined in May.
In March 1912, Alexander met with ten senior military commanders. They agreed to end all internal conflicts in the Royal Serbian Army and fully commit to realising national goals, which allowed space for consolidation before the two successive Balkan Wars.
In the First Balkan War in 1912, as commander of the First Army, Crown Prince Alexander fought victorious battles at Kumanovo and Bitola. One of Alexander's most cherished moments came when he drove the Ottoman Turks out of Kosovo and, on 28 October 1912, led the Serbian army in a review on the Field of Blackbirds. The Field of Blackbirds was where the Serbs under Prince Lazar had been defeated in a legendary battle by the Ottoman sultan Murad I on 28 June 1389, and is regarded by the Serbs as holy ground. It was a great honour for him to pay his respects to the Serbs who had fallen in that earlier battle. In the aftermath of the First Balkan War, disputes emerged among the victors over control of Macedonia, and Serbia and Greece signed an alliance against the Kingdom of Bulgaria.