The First Balkan War (1912-1913) was a conflict in which the Balkan League (Serbia, Montenegro, Greece, Bulgaria) defeated the Ottoman Empire and seized nearly all its remaining European territory, intensifying Balkan nationalism and the Great Power tensions that led to World War I.
The First Balkan War (1912-1913) was the moment the Ottoman Empire, the famous "sick man of Europe," finally got pushed almost entirely out of the continent. Four small states (Serbia, Montenegro, Greece, and Bulgaria) formed the Balkan League and attacked the Ottomans together. They won fast and decisively. The Treaty of London (1913) ended the war and stripped the Ottomans of nearly all their European land.
For AP Euro, the war matters less for its battles and more for what it did to the diplomatic chessboard. Serbia roughly doubled in size and got bolder, which terrified Austria-Hungary, since Austria ruled millions of Slavs who might want to join a Greater Serbia. The victors then immediately fought each other over the spoils in the Second Balkan War (1913). The CED flags this directly under KC-3.4.III.E, which says nationalist tensions in the Balkans drew the Great Powers into a series of crises leading up to World War I. The First Balkan War is one of the biggest of those crises.
This term lives in Unit 7, Topic 7.3 (National Unification and Diplomatic Tensions) and supports learning objective 7.3.B, which asks you to explain how nationalist sentiment and political alliances created tension among European powers from 1815 to 1914. The First Balkan War is the payoff of two long Unit 7 storylines. First, Ottoman decline, which the Crimean War exposed back in the 1850s (KC-3.4.II.A), reaches its endpoint here. Second, the alliance system Bismarck built to keep the peace had, after his dismissal in 1890, hardened into two hostile camps (KC-3.4.III.D). So when Balkan nationalism exploded in 1912, every local quarrel risked dragging in a Great Power patron. Russia backed the Slavs, Austria-Hungary feared Serbia, and Germany backed Austria. The war is the bridge from 19th-century nationalism to the July Crisis of 1914, which makes it a go-to piece of evidence for any causation question about the origins of World War I.
Keep studying AP Euro Unit 7
Balkan League (Unit 7)
The Balkan League was the alliance of Serbia, Montenegro, Greece, and Bulgaria that fought and won this war. Know the four members cold. Their quick victory over the Ottomans is what shocked the Great Powers, and their squabble over the winnings caused the Second Balkan War.
Crimean War (Unit 7)
The Crimean War (1853-1856) first showed Europe that the Ottoman Empire was too weak to hold its territory (KC-3.4.II.A). The First Balkan War is that weakness reaching its logical conclusion sixty years later, with the Ottomans losing almost everything they still held in Europe.
Bismarck's system of alliances (Unit 7)
Bismarck's alliances were designed to keep Balkan disputes from becoming European wars (his Three Emperors' League linked Germany, Austria, and Russia for exactly this reason). After his dismissal in 1890, the system collapsed into rival blocs, so the 1912-1913 Balkan crises had no Bismarck-style referee to contain them.
Nationalism (Units 6-7)
Nationalism unified Italy and Germany earlier in the century, but in the multiethnic Balkans it worked as a wrecking ball instead. The same force that built nation-states tore apart the Ottoman Empire and threatened to do the same to Austria-Hungary, which is why Vienna saw a bigger Serbia as an existential threat.
Expect this term in multiple-choice questions, usually as context for the causes of World War I. Practice questions ask you to identify the Balkan League's members (Serbia, Montenegro, Greece, Bulgaria), the treaty that ended the war (the Treaty of London, 1913), and its significant outcome (the Ottomans lost nearly all their European territory while Serbia grew stronger and more ambitious). No released FRQ has used the term verbatim, but it's prime evidence for an LEQ or DBQ on the causes of WWI or on how nationalism destabilized Europe between 1815 and 1914. The strongest move is causal chaining. Don't just name the war; explain that it emboldened Serbia, alarmed Austria-Hungary, and set the stage for the assassination crisis of 1914.
The First Balkan War (1912-1913) was the Balkan League versus the Ottoman Empire, and the League won. The Second Balkan War (1913) was the winners fighting each other. Bulgaria, unhappy with its share of the spoils, attacked Serbia and Greece and lost badly. Quick check for the exam: First War = against the Ottomans, Second War = among the former allies over the loot.
The First Balkan War (1912-1913) was fought by the Balkan League, made up of Serbia, Montenegro, Greece, and Bulgaria, against the Ottoman Empire.
The Treaty of London (1913) ended the war and removed almost all remaining Ottoman territory in Europe.
Serbia emerged larger and more confident, which alarmed Austria-Hungary because it ruled millions of South Slavs who might want to join Serbia.
The war is direct evidence for KC-3.4.III.E, the idea that nationalist tensions in the Balkans drew the Great Powers into the crises leading up to World War I.
The victors immediately fought each other over the conquered territory in the Second Balkan War of 1913, proving how unstable Balkan nationalism made the region.
On the exam, use the First Balkan War as a link in a causal chain from 19th-century nationalism and Ottoman decline to the outbreak of WWI in 1914.
It was a 1912-1913 war in which the Balkan League (Serbia, Montenegro, Greece, Bulgaria) attacked the declining Ottoman Empire to seize its remaining European territory. Decades of Ottoman weakness plus rising Balkan nationalism made the empire's European lands look like easy pickings.
The Treaty of London (1913) ended the war. It stripped the Ottoman Empire of nearly all its territory in Europe and divided the land among the Balkan League states, which immediately started arguing over the division.
Not directly, but it set the stage. It made Serbia bigger and bolder, deepened Austro-Serbian hostility, and showed that Balkan crises could pull in the Great Powers. The assassination of Archduke Franz Ferdinand in 1914 lit a fuse this war had already laid.
In the First Balkan War (1912-1913), the Balkan League fought the Ottoman Empire and won. In the Second Balkan War (1913), Bulgaria attacked its former allies Serbia and Greece over the division of the spoils and lost.
Serbia, Montenegro, Greece, and Bulgaria. This is a common multiple-choice question, so memorize all four. Note that Romania and the Ottoman Empire were not members.