Question: Which treaty forced Bulgaria to give up most of the territories it had gained in the First Balkan War?
About the article "Balkan Wars", section "Abstract".

Candidate passages:
The Second Balkan War was a conflict which broke out when Bulgaria, dissatisfied with its share of the spoils of the First Balkan War, attacked its former allies, Serbia and Greece, on 16 (O.S.
)/29 June 1913.
Serbian and Greek armies repulsed the Bulgarian offensive and counter-attacked, entering Bulgaria.
With Bulgaria also having previously engaged in territorial disputes with Romania, this war provoked Romanian intervention against Bulgaria.
The Ottoman Empire also took advantage of the situation to regain some lost territories from the previous war.
When Romanian troops approached the capital Sofia, Bulgaria asked for an armistice, resulting in the Treaty of Bucharest, in which Bulgaria had to cede portions of its First Balkan War gains to Serbia, Greece and Romania.
In the Treaty of Constantinople it lost Edirne to the Ottomans. 
Greater Bulgaria was suggested under the Treaty of San Stefano.
The issue of irredentism and nationalism gained greater prominence after the creation of modern Bulgaria following the 1878 Treaty of San Stefano.
However the Congress of Berlin took back some of those territories, returning them to the control of the Ottoman Empire.
In the early 20th century control over Macedonia was a key point of contention between Ottoman Empire, Bulgaria, Greece, and Serbia who fought both the First Balkan War of 1912–1913 and the Second Balkan War of 1913.
The area was further fought over during the Macedonian Campaign of World War I (1915–1918).
Just before entering World War II, Bulgaria had peacefully secured the return of Southern Dobruja from Romania in the Treaty of Craiova.
Greater Bulgaria was re-created as a state during World War II by Nazi Germany, as a reward to Bulgaria, which had fought with Germany as one of the Axis powers.
It was granted territory in Greece, namely Eastern Macedonia and parts of Western Thrace, as well as Yugoslav Macedonia (Vardar Macedonia).
With the exception of the Southern Dobruja, these concessions were reversed with the Allied victory ("see the Paris Peace Conference"). 
The Balkan Wars were two conflicts that took place in the Balkan Peninsula in south-eastern Europe in 1912 and 1913.
Four Balkan states defeated the Ottoman Empire in the first war; one of the four, Bulgaria, was defeated in the second war.
The Ottoman Empire lost nearly all of its holdings in Europe.
Austria-Hungary, although not a combatant, was weakened as a much enlarged Serbia pushed for union of the South Slavic peoples.
The war set the stage for the Balkan crisis of 1914 and thus was a "prelude to the First World War.
"By the early 20th century, Bulgaria, Greece, Montenegro and Serbia had achieved independence from the Ottoman Empire, but large elements of their ethnic populations remained under Ottoman rule.
In 1912, these countries formed the Balkan League.
There were three main causes of the First Balkan War.
The Ottoman Empire was unable to reform itself, govern satisfactorily, or deal with the rising ethnic nationalism of its diverse peoples.
Secondly the Great Powers quarreled amongst themselves and failed to ensure that the Ottomans would carry out the needed reforms.
This led the Balkan states to impose their own solution.
Most important, the Balkan League had been formed, and its members were confident that it could defeat the Turks.
The Ottoman Empire lost almost all its European territories to the west of the River Maritsa, drawing present day Turkey's western border.
A large influx of Turks started to flee into the Ottoman heartland as a result of the lost lands.
By 1914, the remaining core region of the Ottoman Empire had experienced a population increase of around 2.5 million because of the flood of immigration from the Balkans.
In Turkey, it is considered a major disaster ("Balkan harbi faciası") in the nation's history.
The unexpected fall and sudden relinquishing of Turkish-dominated European territories created a psycho-traumatic event amongst the Turks that is said to have triggered the ultimate collapse of the empire itself within five years.
Nazım Pasha, the chief of staff of the Ottoman army has been held responsible of the failure and was assassinated in 1913 by Young Turks.
The First Balkan War broke out when the League attacked the Ottoman Empire on 8 October 1912 and was ended seven months later by the Treaty of London.
After five centuries, the Ottoman Empire lost virtually all of its possessions in the Balkans.
The Second Balkan War broke out on 16 June 1913.
Bulgaria was dissatisfied over the division of the spoils in Macedonia, made in secret by its former allies, Serbia and Greece, and attacked them.
The Serbian and Greek armies repulsed the Bulgarian offensive and counter-attacked into Bulgaria, while Romania and the Ottoman Empire also attacked Bulgaria and gained (or regained) territory.
In the resulting Treaty of Bucharest, Bulgaria lost most of the territories it had gained in the First Balkan War.
The region had been under the rule of the Byzantine Empire from the time of the division of the Roman Empire into Eastern and Western empires in the early fourth century AD.
The Ottoman Empire conquered most of the region in the 14th century and ruled it till the Balkan Wars of 1912–1913.
During Ottoman rule, Thrace had a mixed population of Turks and Bulgarians, with a strong Greek element in the cities and the Aegean Sea littoral.
A smaller number of Pomaks, Jews, Armenians and Romani also lived in the region.
At 1821, several parts of Western Thrace, such as Lavara, Maroneia, and Samothraki rebelled, participated in the Greek War of Independence.
During the First Balkan War, the Balkan League (Serbia, Greece, Bulgaria and Montenegro) fought against the Ottoman Empire and annexed most of its European territory, including Thrace.
Western Thrace was occupied by Bulgarian troops who defeated the Ottoman army.
On November 15, 1912 on the right bank of the river Maritza Macedonian-Adrianopolitan Volunteer Corps captured the Turkish corps of Yaver Paha, which defends the Eastern Rhodopes and Western Thrace from invading Bulgarians.
The victors quickly fell into dispute on how to divide the newly conquered lands, resulting in the Second Balkan War.
In August 1913 Bulgaria was defeated, but gained Western Thrace under the terms of the Treaty of Bucharest.
In the following years, the Central Powers (Germany, Austria-Hungary, Ottoman Empire) (with which Bulgaria had sided) lost World War I and as a result Western Thrace was withdrawn from Bulgaria under the terms of the 1919 Treaty of Neuilly.
Western Thrace was under temporary management of the Entente led by French General Sharpe.
In the second half of April 1920 in San Remo conference of the prime ministers of the main allies of the Entente powers (except USA) Western Thrace was given to Greece.
Throughout the Balkan Wars and World War I, Bulgaria, Greece and Turkey each forced respective minority populations in the Thrace region out of areas they controlled.
A large population of Greeks in Eastern Thrace, and Black Sea coastal and southern Bulgaria, was expelled south and west into Greek-controlled Thrace.
Concurrently, a large population of Bulgarians was forced from the region into Bulgaria by Greek and Turkish actions.
Turkish populations in the area were also targeted by Bulgarian and Greek forces and pushed eastward.
As part of the Treaty of Neuilly, and subsequent agreements, the status of the expelled populations was legitimized.
This was followed by a further population exchange which radically changed the demographics of the region toward increased ethnic homogenization within the territories each respective country ultimately was awarded.
This was followed by the large-scale Greek-Turkish population exchanges of 1923 (Treaty of Lausanne), which finalized the reversal of Western and Eastern Thrace region's pre-Balkan War demography.
The treaty granted the status of a minority to the Muslims in Western Thrace, in exchange for a similar status for the ethnic Greek minority in Istanbul and the Aegean islands of Imbros and Tenedos.
After the German invasion (April 1941), the area was occupied by Bulgarian troops, as part of the triple Axis occupation of Greece, during World War II.
During this period (1941-1944) the demographic destribution was further changed, with the arrest of the region's ca.
4,500 Jews by the Bulgarian police and their deportation to death camps administered by Germany.
None of them survived. 
The continuing collapse of the Ottoman Empire led to two wars in the Balkans, in 1912 and 1913, which in turn was a prelude to world war.
By 1900 nation states had formed in Bulgaria, Greece, Montenegro and Serbia.
Nevertheless many of their ethnic compatriots lived under the control of the Ottoman Empire.
In 1912, these countries formed the Balkan League.
There were three main causes of the First Balkan War.
The Ottoman Empire was unable to reform itself, govern satisfactorily, or deal with the rising ethnic nationalism of its diverse peoples.
Secondly, the Great Powers quarreled among themselves and failed to ensure that the Ottomans would carry out the needed reforms.
This led the Balkan states to impose their own solution.
Most important, the members of the Balkan League were confident that it could defeat the Turks.
Their prediction was accurate, as Constantinople called for terms after six weeks of fighting.
The First Balkan War broke out when the League attacked the Ottoman Empire on 8 October 1912 and was ended seven months later by the Treaty of London.
After five centuries, the Ottoman Empire lost virtually all of its possessions in the Balkans.
The Treaty had been imposed by the Great Powers, and the victorious Balkan states were dissatisfied with it.
Bulgaria was dissatisfied over the division of the spoils in Macedonia, made in secret by its former allies, Serbia and Greece, and attacked them in order to force them out of Macedonia .
The Serbian and Greek armies repulsed the Bulgarian offensive and counter-attacked into Bulgaria, while Romania and the Ottoman Empire also attacked Bulgaria and gained (or regained) territory.
In the resulting Treaty of Bucharest, Bulgaria lost most of the territories it had gained in the First Balkan War.
The long-term result was heightened tension in the Balkans.
Relations between Austria and Serbia became increasingly bitter.
Russia felt humiliated after Austria and Germany prevented it from helping Serbia.
Bulgaria and Turkey were also dissatisfied, and eventually joined Austria and Germany in the First World War.