Preparations for the coup took place between 1901 and 1903. The conspirators decided to place Karadjordje’s grandson, Prince Peter Karadjordjevic, on the throne in November 1901, but he had little trust in them and their initial offers were rebuffed. He accepted their offers on condition that the officers he trusted would take part in the plot and insisted that he would not take any part himself. Prince Peter also told the officers that he would agree to take the throne only if his ascent was approved by the National Assembly. At the time of the coup, he was planning visits to Russia and Romania, suggesting that he was not aware of what was to occur.

The assassination of King Alexander and Queen Draga resulted in the extinction of the Obrenovic line and resolved the century-long feud between the Karadjordjevic and Obrenovic dynasties. Prince Peter expressed regret for the bloodshed that had occurred, describing it as “neither gentlemanly, nor worthy of the 20th century”. On 15 June 1903, by the National Assembly’s decision, Prince Peter was summoned to assume the Serbian throne.

King Peter I was crowned in St. Michael’s Cathedral in Belgrade, on 21 September 1904. The coronation ceremony, the first in Serbia’s modern history, was intended to demonstrate that a new era had begun. The year-long interval between Peter’s return to Serbia and his coronation was done deliberately, so that the ceremony would coincide with the 100th anniversary of the First Serbian Uprising and to give European statesmen time to come to terms with the May Coup. Nevertheless, only representatives of Montenegro and Bulgaria were in attendance. New regalia, consisting of a crown, sceptre, orb and royal mantle, was commissioned specially for the occasion and made by the Parisian jewellers Falize Frères. King Peter’s procession and a parade following the coronation were filmed by Arnold Muir Wilson, the honorary Serbian consul in Sheffield, and his cameraman, Frank Mottershaw. This is believed to the oldest surviving film recorded in Serbia.

The Western-educated King attempted to liberalize Serbia with the goal of creating a Western-style constitutional monarchy. King Peter I became gradually very popular for his commitment to parliamentary democracy that, in spite of certain influence of military cliques in political life, functioned properly. The 1903 Constitution was a revised version of the 1888 Constitution, based on the Belgian Constitution of 1831, considered as one of the most liberal in Europe. The governments were chosen from the parliamentary majority, mostly from People’s Radical Party led by Nikola Pasic and Independent Radical Party led by Ljubomir Stojanovic. King Peter himself was in favour of a broader coalition government that would boost Serbian democracy and help pursue an independent course in foreign policy. In contrast to the Austrophile Obrenovic dynasty, King Peter I was relying on Russia and France, which provoked rising hostility from expansionist-minded Austria-Hungary. King Peter I paid two state visits to Saint-Petersburg and Paris in 1910 and 1911 respectively, greeted as a hero of both democracy and national independence in the troublesome Balkans.

The reign of Peter I, from 1903 to 1914, is remembered as the “Golden Age of Serbia”, due to the unrestricted political freedoms, free press, and cultural ascendancy among South Slavs who finally saw in democratic Serbia a Piedmont of South Slavs. King Peter I was supportive to the movement of Yugoslav unification, hosting in Belgrade various cultural gatherings. Grand School of Belgrade was upgraded into Belgrade University in 1905, with scholars of international renown such as Jovan Cvijic, Mihailo Petrovic, Slobodan Jovanovic, Jovan M. Zujovic, Bogdan Popovic, Jovan Skerlic, Sima Lozanic, Branislav Petronijevic and several others. King Peter I gained enormous popularity following the Balkan Wars in 1912 and 1913, which, from a Serb and South Slav perspective, were a great success, heralded by the spectacular military victories over the Ottomans, followed by the liberation of “Old Serbia” (Kosovo Vilayet) and mostly Slavic-inhabited Macedonia (Manastir Vilayet). The territory of Serbia was doubled and her prestige among South Slavs grew significantly, with Peter I as the main symbol of this both political and cultural success.

The most prominent prime minister during his reign was Nikola Pasic. At the beginning of Peter’s reign he opposed the new king, calling his ascension to the throne unlawful. However, he quickly changed his mind after seeing that the Serbian people accepted King Peter. As it turned out, the only conflict he had with Peter during his 18-year reign was the king’s salary.

A constitutional monarchy was created with the military Black Hand society operating behind the scenes. The traditionally good relations with Austria-Hungary ended, as the new dynasty relied on the support of the Russian Empire and closer cooperation with Kingdom of Bulgaria.

In April 1904 the Friendship treaty and in June 1905 the customs union with Bulgaria were signed. In response Austria-Hungary imposed a Tariff War (Pig war) of 1906-1909. After the 1906 elections the People’s Radical Party came to power. In 1908 Austria-Hungary annexed Bosnia, where Serbia had hoped to expand its territory.

The Bosnian Crisis of 1908–1909 (also referred to as the Annexation crisis) erupted into public view when on 6 October 1908 Austria-Hungary announced the annexation of Bosnia and Herzegovina, which was populated mainly by South Slavs.

Russia, the Ottoman Empire, Britain, the Kingdom of Italy, Serbia, Principality of Montenegro, German Empire and France took an interest in these events. In April 1909, the 1878 Treaty of Berlin was amended to accept the new status quo and bring the crisis to an end. The crisis permanently damaged relations between Austria-Hungary on the one hand and Russia and Serbia on the other. The annexation and reactions to the annexation were some of the contributing causes of World War I.

Following Italy’s victory in the Italo-Turkish War of 1911–1912 the Young Turks fell from power after a coup. The Balkan countries saw this as an opportunity to attack the Ottoman Empire and fulfil their desires of expansion. With the initial encouragement of Russian agents, a series of agreements was concluded between Serbia and Bulgaria in March 1912. Military victory against the Ottoman Empire would not be possible while it could bring reinforcements from Asia. The condition of the Ottoman railways of the time was primitive, so most reinforcement would have to come by sea through the Aegean Sea. Greece was the only Balkan country with a navy powerful enough to deny use of the Aegean to the Ottoman Empire, thus a treaty between Greece and Bulgaria became necessary; it was signed in May 1912. Montenegro concluded agreements between Serbia and Bulgaria later that year. Bulgaria signed treaties with Serbia to divide the territory of northern Macedonia, but refused any similar agreement with Greece.

This alliance between Greece, Serbia, Bulgaria, and Montenegro became known as the Balkan League; its existence was undesirable for all the Great Powers. The League was loose at best, though secret liaison officers were exchanged between the Greek and the Serbian army after the war began. Greece delayed the start of the war several times in the summer of 1912, to better prepare her navy, but Montenegro declared war on 8 October (25 September O.S.). Following an ultimatum to the Ottoman Empire, the remaining members of the alliance entered the conflict on 17 October.

The First Balkan War

On 18 October 1912, King Peter I issued a declaration, “To the Serbian People”. Serbia called upon about 255,000 men (out of a population of 2,912,000 people) grouped in 10 infantry divisions, two independent brigades and a cavalry division, under the effective command of the former War Minister Radomir Putnik. The Serbian High Command, in its pre-war war plans had concluded that the likeliest site of the decisive battle against the Ottoman Vardar Army would be on the Ovce Pole plateau, near Skopje. Hence, the main forces were formed in three armies for the advance towards Skopje, while a division and an independent brigade were to cooperate with the Montenegrins in the Sanjak of Novi Pazar.

The First Army (132,000 men) was the strongest and was commanded by General Petar Bojovic, forming the centre of the drive towards Skopje. The Second Army (74,000 men) was commanded by General Stepa Stepanovic, and consisted of one Serbian and one Bulgarian division. It formed the left wing of the Army and advanced towards Stracin. The Third Army (76,000 men) was commanded by General Bozidar Jankovic and, being the army on the right wing, had the task to take Kosovo. It would then join the other armies in the expected battle at Ovce Polje, where the main forces of Ottoman Vardar Army were expected to concentrate.

According to the plan of the Serbian Supreme Command, three Serbian armies (First, Second and Third) were supposed to encircle and destroy the Vardar Army in that area, with the First Army advancing from the north (direction Vranje-Kumanovo-Ovce Pole), the Second Army advancing from the east (direction Kriva Palanka-Kratovo-Ovce Pole) and the Third Army advancing from the north-west (direction Pristina-Skopje-Ovce Pole). In the execution of this plan the main role was given to the First Army while the Second Army was expected to cut off the Vardar Army’s retreat route, and if necessary attack its rear and right flank. The main goal of the Third Army was to take Kosovo and Metohija and if necessary give assistance to the First Army by attacking the Vardar Army’s left flank and rear.

The Serbian Army under General (later Marshal) Putnik dealt three decisive victories (battles of Kumanovo, Prilep and Monastir) in Vardar Macedonia, its primary objective in the war, effectively destroying the Ottoman forces in the region and conquering north Macedonia. They also helped the Montenegrins to take the Sanjak and sent two divisions to help the Bulgarians at the siege of Edirne.

The last battle for Macedonia was the battle of Monastir, in which the remains of the Ottoman Vardar Army were forced to retreat to central Albania. After the battle, Prime Minister Pasic asked Gen. Putnik to take part in the race for Thessaloniki. Putnik declined and instead turned his army to the west, towards Albania, foreseeing that a future confrontation between the Greeks and Bulgarians over Thessaloniki could greatly help Serbia’s own plans over Vardar Macedonia.

The Treaty of London ended the First Balkan War on 30 May 1913. All Ottoman territory west of the Enez-Kıyıköy line was ceded to the Balkan League, according to the status quo at the time of the armistice. The treaty also declared Albania to be an independent state. Almost all of the territory that was designated to form the new Albanian state was currently occupied by either Serbia or Greece, which only reluctantly withdrew their troops. Having unresolved disputes with Serbia over the division of northern Macedonia and with Greece over southern Macedonia, Bulgaria was prepared, if the need arose, to solve the problems by force, and began transferring its forces from Eastern Thrace to the disputed regions. Unwilling to yield to any pressure Greece and Serbia settled their mutual differences and signed a military alliance directed against Bulgaria on 1 May 1913, even before the Treaty of London had been concluded. This was soon followed by a treaty of “mutual friendship and protection” on 19 May 1913. Thus the scene for the Second Balkan War was set.

The Second Balkan War

The relations between the victorious Balkan allies quickly soured over the division of the spoils, especially in Macedonia. During the pre-war negotiations that had resulted in the establishment of the Balkan League, Serbia and Bulgaria signed a secret agreement on 13 March 1912 which determined their future boundaries, in effect sharing northern Macedonia between them. In case of a post-war disagreement, the area to the north of the Kriva Palanka-Ohrid line (with both cities going to the Bulgarians), had been designated as a “disputed zone” under Russian arbitration and the area to the south of this line had been assigned to Bulgaria. During the war, the Serbs succeeded in capturing an area far south of the agreed border, down to the Bitola-Gevgelija line (both in Serbian hands). At the same time, the Greeks advanced north, occupying Thessaloniki shortly before the Bulgarians arrived, and establishing a common Greek border with Serbia.

When Bulgarian delegates in London bluntly warned the Serbs that they must not expect Bulgarian support on their Adriatic claims, the Serbs angrily replied that that was a clear

withdrawal from the pre-war agreement of mutual understanding according to the Kriva Palanka-Adriatic line of expansion, but the Bulgarians insisted that in their view, the Vardar Macedonian part of the agreement remained active and the Serbs were still obliged to surrender the area as agreed. The Serbs answered by accusing the Bulgarians of maximalism, pointing out that if they lost both northern Albania and Vardar Macedonia, their participation in the common war would have been virtually for nothing.

When Bulgaria called upon Serbia to honour the pre-war agreement over northern Macedonia, the Serbs, displeased at the Great Powers’ requiring them to give up their gains in northern Albania, adamantly refused to alienate any more territory. The developments essentially ended the Serbo-Bulgarian alliance and made a future war between the two countries inevitable. Soon thereafter, minor clashes broke out along the borders of the occupation zones with the Bulgarians against the Serbs and the Greeks. Responding to the perceived Bulgarian threat, Serbia started negotiations with Greece, which also had reasons to be concerned about Bulgarian intentions.

On 19 May 1913, two days after the signing of the Treaty of London and just 28 days before the Bulgarian attack, Greece and Serbia signed a secret defensive alliance, confirming the current demarcation line between the two occupation zones as their mutual border and concluding an alliance in case of an attack from Bulgaria or from Austria-Hungary. With this agreement, Serbia succeeded in making Greece a part of its dispute over northern Macedonia, since Greece had guaranteed Serbia’s current (and disputed) occupation zone in Macedonia. In an attempt to halt the Serbo-Greek rapprochement, Bulgarian Prime Minister Geshov signed a protocol with Greece on 21 May agreeing on a permanent demarcation between their respective forces, effectively accepting Greek control over southern Macedonia. However, his later dismissal put an end to the diplomatic targeting of Serbia.

Another point of friction arose: Bulgaria’s refusal to cede the fortress of Silistra to Romania. When Romania demanded its cession after the First Balkan War, Bulgaria’s foreign minister offered instead some minor border changes, which excluded Silistra, and assurances for the rights of the Kutzovlachs in Macedonia. Romania threatened to occupy Bulgarian territory by force, but a Russian proposal for arbitration prevented hostilities. In the resulting Protocol of St. Petersburg of 8 May 1913, Bulgaria agreed to give up Silistra. The resulting agreement was a compromise between the Romanian demands for the entire southern Dobruja and the Bulgarian refusal to accept any cession of its territory. However the fact that Russia failed to protect the territorial integrity of Bulgaria made the Bulgarians uncertain of the reliability of the expected Russian arbitration of the dispute with Serbia. The Bulgarian behaviour had also a long-term impact on the Russo-Bulgarian relations. The uncompromising Bulgarian position to review the pre-war agreement with Serbia during a second Russian initiative for arbitration between them finally led Russia to cancel its alliance with Bulgaria. Both acts made conflict with Romania and Serbia inevitable.

The main Bulgarian attack was planned against the Serbs with their 1st, 3rd, 4th and 5th Armies, while the 2nd Army was tasked with an attack towards Greek positions around

Thessaloniki. However, in the crucial opening days of the war, only the 4th Army and 2nd Army were ordered to advance. This allowed the Serbs to concentrate their forces against the attacking Bulgarians and hold their advance. The Bulgarians were outnumbered on the Greek front, and the low-level fighting soon turned into Greek attack all along the line on 19 June. The Bulgarian forces were forced to withdraw from their positions north of Thessaloniki to defensive positions between Kilkis and Struma river. The plan to quickly destroy the Serbian army in central Macedonia by concentrated attack turned out to be unrealistic, and the Bulgarian Army started to retreat even before Romanian intervention, and the Greek advance necessitated disengagement of forces in order to defend Sofia.

The 4th Bulgarian Army held the most important position for the conquest of Serbian Macedonia. The fighting began on 29-30 June 1913, between the 4th Bulgarian Army and the 1st and 3rd Serbian armies, first along the Zletovska and then after a Bulgarian retreat, along the Bregalnica. Internal confusions led to heavy Bulgarian losses in 1–3 July. The Serbs captured the whole 7th Division of the 4th Bulgarian Army, without any fight. By 8 July, the Bulgarian Army had been severely defeated.

On the north the Bulgarians started to advance towards the Serbian border town of Pirot and forced Serbian Command to send reinforcements to the 2nd Army defending Pirot and Nis. This enabled Bulgarians to stop the Serbian offensive in Macedonia at Kalimanci on 18 July.

Romania mobilized its army on 5 July 1913, intending to seize Southern Dobruja, and declared war on Bulgaria on 10 July. On 20 July they occupied Vratsa, 116 km north of Sofia. On 23 July, advanced cavalry forces had entered Vrazhdebna, a suburb just seven miles from Sofia. The Romanians and Serbs linked up at Belogradchik on 25 July, isolating the important city of Vidin. The Bulgarian rear was entirely exposed, no resistance had been offered, the capital was open to the invader and the north-western corner of the country was cut off and surrounded.

With the Romanian army closing in on Sofia, Bulgaria asked Russia to arbitrate. On 20 July, via Saint Petersburg, the Serbian Prime Minister Nikola Pasic invited a Bulgarian delegation to treat with the allies directly at Nis in Serbia. The Serbs and Greeks, both now on the offensive, were in no rush to conclude a peace. On 22 July, Tsar Ferdinand sent a message to King Carol via the Italian ambassador in Bucharest. The Romanian armies halted before Sofia. Romania proposed that talks be moved to Bucharest, and the delegations took a train from Nis to Bucharest on 24 July.

When the delegations met in Bucharest on 30 July, the Serbs were led by Pasic, the Montenegrins by Vukotic, the Greeks by Venizelos, the Romanians by Maiorescu and the Bulgarians by Finance Minister Tonchev. They agreed to a five-day armistice to come into effect on 31 July. Romania refused to allow the Ottomans to participate, forcing Bulgaria to negotiate with them separately.

Bulgaria had agreed to cede Southern Dobruja to Romania as early as 19 July. At the peace talks in Bucharest, the Romanians, having obtained their primary objective, were a voice for moderation. The Bulgarians hoped to keep the Vardar river as the boundary between their share of Macedonia and Serbia’s. The latter preferred to keep all of Macedonia as far as the Struma. Austro-Hungarian and Russian pressure forced Serbia to be satisfied with most of northern Macedonia, conceding only the town of Stip to the Bulgarians.

The last day of negotiations was 8 August. On 10 August Bulgaria, Greece, Montenegro, Romania and Serbia signed the Treaty of Bucharest and divided Macedonia in three: Vardar Macedonia went to Serbia; the smallest part, Pirin Macedonia, to Bulgaria; and the coastal and largest part, Aegean Macedonia, to Greece. Bulgaria thus enlarged its territory by 16 percent compared to what it was before the First Balkan War, and increased its population from 4.3 to 4.7 million people. Romania enlarged her territory by 5 percent and Montenegro by 62 percent. Greece increased her population from 2.7 to 4.4 million and her territory by 68 percent. Serbia almost doubled her territory enlarging her population from 2.9 to 4.5 million.

The Second Balkan War left Serbia as the most militarily powerful state south of the Danube. Years of military investment financed by French loans had borne fruit. Central Vardar and the eastern half of the Sanjak of Novi Pazar were acquired. Its territory grew in extent from 18,650 to 33,891 square miles and its population grew by more than one and a half million.

Serbia made additional gains in northern Macedonia and having fulfilled its aspirations to the south, turned its attention to the north where its rivalry with Austro-Hungary over Bosnia-Herzegovina led the two countries to war a year later igniting the First World War.

At the strong insistence of Austria-Hungary and Italy, both hoping to control for themselves the state and thus the Otranto Straits in Adriatic, Albania acquired officially its independence according to the terms of the Treaty of London. With the delineation of the exact boundaries of the new state under the Protocol of Florence (17 December 1913), the Serbs lost their outlet to the Adriatic and the Greeks the region of Northern Epirus (Southern Albania).

After its defeat, Bulgaria turned into a revanchist local power looking for a second opportunity to fulfil its national aspirations. To this end, it participated in the First World War on the side of the Central Powers, since its Balkan enemies (Serbia, Montenegro, Greece, and Romania) were pro-Entente.