1903 military coup against King Alexander I of Serbia; Peter I installed
The May Coup () was a coup d'état in the Kingdom of Serbia which resulted in the assassination of King Alexander I and his consort, Queen Draga, inside the Stari Dvor in Belgrade on the night of 10–11 June [O.S. 28–29 May] 1903. This act resulted in the extinction of the Obrenović dynasty that had ruled Serbia since the middle of the 19th century. A group of Royal Serbian Army officers led by Captain Dragutin Dimitrijević (Apis) organized the assassination. After the May Coup, the throne passed to King Peter I of the Karađorđević dynasty.
Along with the royal couple, the conspirators killed prime minister Dimitrije Cincar-Marković, minister of the army Milovan Pavlović, and general-adjutant Lazar Petrović. The coup had a significant influence on Serbia's relations with other European powers; the Obrenović dynasty had mostly allied with Austria-Hungary, while the Karađorđević dynasty had close ties both with Russia and with France. Each dynasty received ongoing financial support from their powerful foreign sponsors.
Background.
When Serbia gained independence from Ottoman Turkish control following the Serbian Revolution in 1804 to 1835, it emerged as an independent principality ruled by various factions surrounding the Obrenović and Karađordević dynasties. They, in turn, were sponsored by the rival Austro-Hungarian and Russian empires. The Obrenović family was mostly pro-Austrian, and their hereditary enemies, the Karađordević family, was mostly pro-Russian. Each dynasty was financially aided by their powerful foreign sponsors.
After the assassination of Prince Mihailo Obrenović on 29 May 1868 (Old Style), his cousin, Milan Obrenović, became the newly-elected Serbian prince. Milan was married to Natalie Keshko, a Moldavian boyar's daughter. He was an autocratic ruler and unpopular among the people. During his rule, Serbia re-emerged as an independent country and gained territory at the 1878 Congress of Berlin.
Since Russia gave its support to Bulgaria at the Treaty of San Stefano, King Milan relied on Austria-Hungary as his ally. He proclaimed himself King in 1882. His military defeats in the Serbo-Bulgarian War and the Timok Rebellion, led by elements of the People's Radical Party, were serious blows to his popularity.
The situation was compounded by quarrels between the King and the Queen. King Milan was not a faithful husband and Queen Natalija was greatly influenced by Russia. In 1886, the couple, mismatched both personally and politically, separated. Queen Natalija withdrew from the kingdom, taking with her the ten-year-old Prince Alexander (later King Alexander I). While she was residing in Wiesbaden in 1888, King Milan was successful in recovering the Crown Prince, whom he undertook to educate. As a reply to the queen's remonstrances, Milan exerted considerable pressure upon the Metropolitan and obtained a divorce which was later declared illegal.
On 3 January 1889, Milan adopted the new constitution which was much more liberal than the existing 1869 Constitution. Two months later, on 6 March, Milan suddenly abdicated the throne in favor of his son. No satisfactory reason was given for that step. Upon the abdication, former King Milan put up a regency to rule in the name of young King Alexander and retired to Paris to live as an ordinary citizen. Members of the regency were Jovan Ristić, General Kosta Protić and General Jovan Belimarković. The Radicals were forgiven and allowed to return to political life. The Radical Sava Grujić formed a new government, which was succeeded by the Government of Nikola Pašić, the leader of the Radical Party. After King Milan's pro-Austrian policy, the Radical-led Government became closer to the Russian Empire. In the summer of 1891, Prince Alexander and Pašić visited Russian Tsar Alexander III. The Tsar promised that Russia would not allow Austro-Hungarian annexation of Bosnia and Herzegovina and that Russia would support Serbian interests in "Old Serbia" and Macedonia.
Alexander's mother, former queen Natalija, who was in the process of divorcing Milan and was banished from Belgrade, upon Alexander's request went to the French coastal resort Biarritz together with her lady-in-waiting and the future queen Draga Mašin.
After the death of the Regent Protić on 4 June 1892, a conflict emerged between Pašić, who wanted the vacant position in the regency for himself, and the Regent Ristić, who disliked Pašić. In 1892, Ristić transferred the government to the Liberal Party, the party he had always been linked with, and appointed Jovan Avakumović as the new prime minister. This step and the subsequent conduct of the Liberal politicians caused serious discontent in the country. On the 1st (13th) of April 1893, Prince Alexander, by a successful stratagem, imprisoned the regents and the ministers in the palace and, declaring himself of age, called the Radicals to office. In quick succession, the new prime ministers were Radicals Lazar Dokić, Sava Grujić, Đorđe Simić and Svetozar Nikolajević. One of the guardsmen that helped Alexander imprison the regents and the ministers was colonel Lazar "Laza" Petrović.
At the beginning of his reign, King Alexander was prescribing a program of Government in matters of the military, the economical and the financial life of the state. He disapproved an unprincipled party competition and in order to suppress the Radicals, on 9 January, he invited his father back to Serbia. The Radical Government immediately resigned and moved into opposition. The influence of former king Milan in state affairs could be seen immediately after his return to Serbia.
King Alexander tried to keep a policy of neutral governments but he did not have much success. Therefore, on 9 May 1894 he conducted another coup, abolished the Constitution from 1888, and put into force the old one from 1869. Milan's return to Serbia did not last long because he quickly got into a conflict with his son. A week after his departure, Queen Natalija was allowed to return to Serbia. Natalija invited Alexander to come to Biarritz. When he visited his mother, he met Draga, 9 years his senior, and immediately fell in love with her. Natalija knew about the affair but did not pay much attention to it, believing that it would be short-lived.
In the meantime, the progressivist Stojan Novaković formed a new government. On his father's command, King Alexander visited Vienna where, as a sign of Austro-Serbian friendship, he awarded the Austrian minister of finance Béni Kállay, who was also the minister for Bosnia and Herzegovina. This was poorly received in Serbia because of the Austro-Hungarian tendency to annex Bosnia and Herzegovina.
Marriage to Draga Mašin Lunjevica.
King Alexander invited his father to return once more to Serbia. Upon the arrival of former King Milan in Serbia on 7 October 
1897, a new Government was formed with Vladan Đorđević as the new prime minister. Milan was appointed to the position of Supreme Commander of the Active Army of the Kingdom of Serbia. Together with the new Government, Milan tried to find a suitable princess from some Western court to become Alexander's bride, not knowing that Alexander was already meeting regularly with Draga.
Due to the growing involvement of former king Milan in daily Serbian political life, and especially due to his anti-Radical policy, an unemployed worker tried to assassinate Milan on 24 June 1899, resulting in Milan to begin reckoning with the Radicals in every way. However, Alexander now had to find a way to get rid of his father so that he could marry Draga. He decided to send King Milan and Prime Minister Đorđević outside the country. Under the pretext of negotiating his marriage to the German Princess Alexandra Caroline zu Schaumburg-Lippe, sister of Queen Charlotte of Württemberg, Alexander sent his father to Karlsbad and Prime Minister Đorđević to Marienbad to sign a contract with Austria-Hungary. As soon as he removed the opponents, Alexander was able to announce his engagement to Draga Mašin.
King Alexander's popularity further declined after his marriage to Draga, the former lady-in-waiting of his mother Queen Natalija and widow of engineer Svetozar Mašin. Draga was nine years older than Alexander. At that time, it was very unusual for a king or heir to the throne to marry a woman who was not a member of the nobility. Alexander's father, the former King Milan, did not approve of the marriage and refused to return to Serbia. He died in Vienna in 1901. Another opponent of the marriage was the dowager queen Natalija, who wrote a letter to Alexander containing all of the ugliest rumors regarding Draga circulating in Russia. Minister of foreign affairs Andra Đorđević visited Jakov Pavlović, archbishop of Belgrade and metropolitan of Serbia, and asked him to refuse to grant his blessing. Alexander also visited the metropolitan and threatened that he would abdicate if he could not receive his blessing. As a sign of protest, the entire Đorđević government resigned. Among the fiercest opponents to the marriage was Đorđe Genčić, minister of the interior in Đorđević's government. Because of Genčić's public condemnation of the engagement, Alexander had him jailed for seven years. The situation was resolved by Russian tsar Nicholas II, who agreed to be Alexander's honorary best man.
The wedding took place on 23 July 1900. One of the officers in the procession was Dragutin Dimitrijević Apis. With strained relations with the outside world because of his unpopular marriage, King Alexander's foreign policy turned to Russia. The king had previously released the Radicals from prison who had been accused of backing the Ivandan assassination attempt on former King Milan.
After the death of his father Milan, King Alexander, as a sign of goodwill because of the queen's alleged pregnancy (a public secret existed that she was actually sterile since an accident in her youth, which Alexander refused to believe), pardoned all political prisoners, including Đorđe Genčić and the remaining Radicals. On 20 March 1901, he assembled a new government led by the Radical Mihailo Vujić. The government consisted of representatives from the People's Radical Party and the Liberal Party. King Alexander then enacted a new octroyed constitution, with its main feature the introduction of a bicameral system consisting of the Senate (upper house) and the National Assembly (lower house). The new constitution gave the monarch the right to appoint the majority of the senators, who would defend his interests.
The false pregnancy of Queen Draga created a major problem for King Alexander. The first reaction came from the Russian tsar, who did not want to receive the king and queen upon their planned visit to Russia. Alexander blamed Radicals for it, instigated a new coup, and installed a government headed by general Dimitrije Cincar-Marković on 6 November 1902.
Because of increasing repulsion by the Russian court, King Alexander again tried to approach Austria in the autumn of 1902. He had taken some earlier steps in January 1902 when he sent his personal secretary to Vienna with the promise that it would solve the question of his successor in agreement with the neighbouring monarchy by adopting one of the descendants of the female line of Obrenovićs living in Austria-Hungary. Draga believed that Alexander should adopt her brother Nikodije Lunjevica for the succession.
Dimitrije Tucović organized a rally of dissatisfied workers and students on 23 March 1903, which escalated to open conflict with the police and the army, resulting in the deaths of six people. Knowing that he would not be able to win new elections, the king staged two coups within one hour. With the first coup, Alexander abolished his octroyed constitution and disbanded the Senate and National Assembly. Then the king appointed new members to the Senate, the state council and the courts. In the second coup, the king restored the constitution that he had abolished just a few hours earlier. Following this, the government held elections on 18 May 1903 (31 May by the Gregorian calendar), which the government won. This was the final political victory for King Alexander I.
Army officers' conspiracy.
Junior officers had complained that the queen's false pregnancy diminished the international reputation of Serbia. They were also unhappy with the constant temper tantrums thrown by her brother Nikola Lunjevica, himself a junior military officer who once killed a policeman whilst drunk. Nikola, as the king's brother-in-law, had also demanded that senior officers report and salute to him.
In August 1901, cavalry lieutenant Antonije Antić (Genčić's nephew), captains Radomir Aranđelović and Milan Petrović and lieutenants Dragutin Dimitrijević Apis and Dragutin Dulić organised a plot to assassinate the king and queen.
The first meeting was on 6 September 1901 in Lieutenant Antić's apartment. Later, lieutenant Milan Marinković and lieutenant Nikodije Popović