Here is a link to the Convenant of the League of Nations
http://avalon.law.yale.edu/20th_century/leagcov.asp

Brief Summary of the Major conflicts avoided through the League of Nations

Corfu, 1923
The Dispute:
An Italian general was killed while he was doing some work for the League in Greece. The Italian leader Mussolini was angry with the Greeks. He invaded the Greek island of Corfu, which Mossolini saw as acceptable for their was a considerable Italian population living there.

The Greeks asked the League to help.

What the League did:
The Council of the League met. It condemned Mussolini, and told him to leave Corfu.
It told the Greeks to give some money to the League.

What happened:
Mussolini refused to accept its decision. He refused to leave Corfu.
The League changed its decision. It told Greece to apologise to Mussolini, and to pay the money to Italy.
The Greeks did as the League said. Then Mussolini gave Corfu back to Greece.


Bulgaria, 1925
The Dispute:
Some Greek soldiers were killed in a small fight on the border between Greece and Bulgaria. The Greeks were angry. They invaded Bulgaria.
Bulgaria asked the League to help.
What the League did:
The Council of the League met. It condemned the Greeks, and told them to leave Bulgaria.
What happened:
The Bulgarian government sent orders to its army not to fight back.
The Greeks did as the League said. They left Bulgaria.


Tarlis incident

The Tarlis incident is the name given to the killing of 17 Bulgarian peasants by a Greek officer on July 27, 1924 at Tarlis (present-day Vathitopos), a mountainous village in the Drama region near Greek-Bulgarian borders.

Background

Tarlis (Τрлис), Loftsa and Karakioi were three Bulgarian villages deadlocked inside Greek territory after Greco-Bulgarian borders had been drawn in accordance with the Treaty of Bucharest (1913).
Out of a total population of 800, only 50 were Greek - recently settled refugees from the Ottoman empire.
Martial law was imposed in Greece by the Themistoklis Sophoulis government that took office three day earlier on July 24, 1924.

Incident

Official Greek reports stated that on Saturday evening of July 26, 1924, residents of Tarlis had been gathered in the village’s square discussing the issue of repatriation between Greece and Bulgarian according the 1919 Treaty of Neuilly which provided for the voluntary exchange of populations between Greece and Bulgaria. The deadline of admission for resettlement was ended five days later on August 31, 1924.
Suddenly some shots and explosions were heard from a nearby gorge. Major Kalabalikis, the Greek officer in charge of region, ordered the arrest of 70 Bulgarian peasants from three villages, suspected as being responsible.
The next day, Sunday July 27, 1924, Kalabalikis ordered his military aide lieutenant Doksakis, a Greek officer from Crete, to move 27 captured villagers and bring them to the district administration in Serres for interrogation, via Gorno Brodi village.
Doksakis at the head of 10 Greek soldiers led bound captives via a mountain trail bypassing the public road between Tarlis and Gorno Vrondi. He returned five hours later to announce that his squad was attacked by Bulgarian commitadzis, and that when detainees tried to escape he was forced to kill 17 of them.

Reaction

The Tarlis incident triggered heavy protests in Bulgaria and international outcry against Greece. The Common Greco-Bulgarian committee for emigration investigated the incident and presented its conclusions to League of Nations in Geneva.
As a result a bilateral Bulgarian-Greek agreement was signed in Geneva on September 29, 1925 known as Politis-Kalfov protocol after the League of Nations demand, recognizing Greek slavophones as Bulgarians and guaranteeing their protection. Next month a Bulgarian primer textbook in Latin known as Abecedar published by the Greek ministry for education, was introduced to Greek schools of Aegean Macedonia.
On February 2, 1925, the Greek parliament, under pressure from Serbia, rejected ratification of the 1913 Greek-Serbian Coalition Treaty. Agreement lasted 9 months until June 10, 1925 when League of Nations annulled it.




The incident at Petrich, or the War of the Stray Dog, was the short invasion of Bulgaria by Greece near the border town Petrich in 1925. The incident was a result of the minority problems that caused many disputes between Greece and Bulgaria in the post-World War I era.

The incident

It allegedly started on October 22, when a Greek soldier ran after his dog, which had strayed across the border from Macedonia; thus, it is sometimes referred to as the War of the Stray Dog. The border was guarded by Bulgarian sentries, and one of them shot the Greek soldier. According to the Greek army a Greek captain was also shot.
Given the tense political climate, escalation was inevitable; in response, the Greek dictatorial government under General Theodoros Pangalos sent soldiers into Bulgaria and tried to occupy Petrich. He also sent message to the Bulgarian side demanding:
  1. The punishment of the Bulgarian commanders of the troops that shot the Greek soldiers.
  2. Official apology from the Bulgarian government for the incident.
  3. Six million Drachmas as compensation for the families of the victims.
Bulgaria was given 48 hours to accept the Greek demands.

International intervention

Bulgaria ordered its troops to provide only token resistance, trusting the League of Nations to settle the dispute. Otherwise some chetas of Internal Macedonian Revolutionary Organization (IMRO), together with the sentries organised defence lines against the Greeks near Petrich, which halted the Greeks from entering the town. Volunteers and war veterans from the whole region were summoned to join the resistance. On the other side Greece made clear that it was not interested in Bulgarian territory but demands the compensation.
The League did indeed condemn the Greek invasion, and called for both Greek withdrawal and compensation to Bulgaria. Greece ceded to this demand and was imposed a fine of £45,000. Over 50 people were killed before Greece complied, mostly Bulgarian civilians. Greece complained about the disparity between its treatment and that of Italy in the Corfu incident in 1923, when the Italian armed forces occupied the Greek island of Corfu in retaliation for the murder of Italian general Enrico Tellini while surveying the Greek border with Albania.

There was a boundary dispute between Greece and Albania. The two nations took their dispute to the Conference of Ambassadors. The Conference of Ambassadors created a commission to determine the boundary, which was authorized by the League of Nations to settle the dispute. Several countries (including Italy) provided small detachments of soldiers to assist the commission in carrying out the survey.

The incident in Greece

On August 27, in 1923 the Italian general, Enrico Tellini, and three of his assistants were murdered by unknown assailants at Kakavia within Greek territory. They were attacked, according to some sources by Greek nationalists and, according to some others, by Albanian bandits.

Italian reaction

Italy sent an ultimatum to Greece on August 29, 1923, demanding 50 million lire in reparations and execution of the killers. Greece was unable to identify the killers, so Italian forces bombarded and occupied the Greek island of Corfu on August 31, 1923, killing at least fifteen civilians. The ulterior motive for the invasion was Corfu's strategic position at the entrance of the Adriatic Sea. Tellini's assassination is considered a convenient pretext.

Resolution

Greece appealed to the League of Nations, which initially condemned the Italian occupation. The dispute was handed over to the Conference of Ambassadors, and Italy and Greece agreed to be bound by its decision. The Conference largely followed the nominal Italian demands, ordering Greece to apologise and pay reparations, a decision that Greece accepted.
Italian forces left Corfu on September 27, 1923.
This decision was internationally criticized: in effect the world community had accepted Italy's aggression against Greece, instead of protecting the smaller country.
In Corfu during the first quarter of the twentieth century, many Italian operas were performed at the Municipal Theatre of Corfu. This tradition came to a halt following the Corfu incident. After the bombardment the theatre featured Greek operas as well as Greek theater performances by distinguished Greek actors such as Marika Kotopouli and Pelos Katselis.


The Aaland Islands (1921)
These islands are near enough equal distant between Finland and Sweden. They had traditionally belonged to Finland but most of the islanders wanted to be governed by Sweden. Neither Sweden nor Finland could come to a decision as to who owned the islands and in 1921 they asked the League to adjudicate. The League’s decision was that they should remain with Finland but that no weapons should ever be kept there. Both countries accepted the decision and it remains in force to this day.
Upper Silesia (1921)
The Treaty of Versailles had given the people of Upper Silesia the right to have a referendum on whether they wanted to be part of Germany or part of Poland. In this referendum, 700,000 voted for Germany and 500,000 for Poland. This close result resulted in rioting between those who expected Silesia to be made part of Germany and those who wanted to be part of Poland. The League was asked to settle this dispute. After a six-week inquiry, the League decided to split Upper Silesia between Germany and Poland. The League’s decision was accepted y both countries and by the people in Upper Silesia.
Memel (1923)
Memel was/is a port in Lithuania. Most people who lived in Memel were Lithuanians and, therefore, the government of Lithuania believed that the port should be governed by it. However, the Treaty of Versailles had put Memel and the land surrounding the port under the control of the League. For three years, a French general acted as a governor of the port but in 1923 the Lithuanians invaded the port. The League intervened and gave the area surrounding Memel to Lithuania but they made the port an "international zone". Lithuania agreed to this decision. Though this can be seen as a League success – as the issue was settled – a counter argument is that what happened was the result of the use of force and that the League responded in a positive manner to those (the Lithuanians) who had used force.
Turkey (1923)
The League failed to stop a bloody war in Turkey (see League failures) but it did respond to the humanitarian crisis caused by this war.
1,400,000 refugees had been created by this war with 80% of them being women and children. Typhoid and cholera were rampant. The League sent doctors from the Health Organisation to check the spread of disease and it spent £10 million on building farms, homes etc for the refugees. Money was also invested in seeds, wells and digging tools and by 1926, work was found for 600,000 people.
A member of the League called this work "the greatest work of mercy which mankind has undertaken."
Greece and Bulgaria (1925)

Both these nations have a common border. In 1925, sentries patrolling this border fired on one another and a Greek soldier was killed. The Greek army invaded Bulgaria as a result. The Bulgarians asked the League for help and the League ordered both armies to stop fighting and that the Greeks should pull out of Bulgaria. The League then sent experts to the area and decided that Greece was to blame and fined her £45,000. Both nations accepted the decision.


The failures of the League of Nations
Article 11 of the League’s Covenant stated:


"Any war of threat of war is a matter of concern to the whole League and the League shall take action that may safe guard peace."


Therefore, any conflict between nations which ended in war and the victor of one over the other must be considered a League failure.
Italy (1919)
In 1919, Italian nationalists, angered that the "Big Three" had, in their opinion, broken promises to Italy at the Treaty of Versailles, captured the small port of Fiume. This port had been given to Yugoslavia by the Treaty of Versailles. For 15 months, Fiume was governed by an Italian nationalist called d’Annunzio. The newly created League did nothing. The situation was solved by the Italian government who could not accept that d’Annunzio was seemingly more popular than they were – so they bombarded the port of Fiume and enforced a surrender. In all this the League played no part despite the fact that it had just been set up with the specific task of maintaining peace.
Teschen (1919)
Teschen was a small town between Poland and Czechoslovakia. Its main importance was that it had valuable coal mines there which both the Poles and the Czechs wanted. As both were newly created nations, both wanted to make their respective economies as strong as possible and the acquisition of rich coal mines would certainly help in this respect.
In January 1919, Polish and Czech troops fought in the streets of Teschen. Many died. The League was called on to help and decided that the bulk of the town should go to Poland while Czechoslovakia should have one of Teschen’s suburbs. This suburb contained the most valuable coal mines and the Poles refused to accept this decision. Though no more wholesale violence took place, the two countries continued to argue over the issue for the next twenty years.
Vilna (1920)
Many years before 1920, Vilna had been taken over by Russia. Historically, Vilna had been the capital of Lithuania when the state had existed in the Middle Ages. After World War One, Lithuania had been re-established and Vilna seemed the natural choice for its capital.
However, by 1920, 30% of the population was from Poland with Lithuanians only making up 2% of the city’s population. In 1920, the Poles seized Vilna. Lithuania asked for League help but the Poles could not be persuaded to leave the city. Vilna stayed in Polish hands until the outbreak of World War Two. The use of force by the Poles had won.
War between Russia and Poland (1920 to 1921)
In 1920, Poland invaded land held by the Russians. The Poles quickly overwhelmed the Russian army and made a swift advance into Russia. By 1921, the Russians had no choice but to sign the Treaty of Riga which handed over to Poland nearly 80,000 square kilometres of Russian land. This one treaty all but doubled the size of Poland.
What did the League do about this violation of another country by Poland?
The answer is simple – nothing. Russia by 1919 was communist and this "plague from the East" was greatly feared by the West. In fact, Britain, France and America sent troops to attack Russia after the League had been set up. Winston Churchill, the British War Minister, stated openly that the plan was to strangle Communist Russia at birth. Once again, to outsiders, it seemed as if League members were selecting which countries were acceptable and ones which were not. The Allied invasion of Russia was a failure and it only served to make Communist Russia even more antagonistic to the West.
The invasion of the Ruhr (1923)
The Treaty of Versailles had ordered Wiemer Republic to pay reparations for war damages. These could either be paid in money or in kind (goods to the value of a set amount) In 1922, the Germans failed to pay an installment. They claimed that they simply could not rather than did not want to. The Allies refused to accept this and the anti-German feeling at this time was still strong. Both the French and the Belgium’s believed that some form of strong action was needed to ‘teach Germany a lesson’.
In 1923, contrary to League rules, the French and the Belgium’s invaded the Ruhr – Germany’s most important industrial zone. Within Europe, France was seen as a senior League member – like Britain – and the anti-German feeling that was felt throughout Europe allowed both France and Belgium to break their own rules as were introduced by the League. Here were two League members clearly breaking League rules and nothing was done about it.
For the League to enforce its will, it needed the support of its major backers in Europe, Britain and France. Yet France was one of the invaders and Britain was a major supporter of her. To other nations, it seemed that if you wanted to break League rules, you could. Few countries criticised what France and Belgium did. But the example they set for others in future years was obvious. The League clearly failed on this occasion, primarily because it was seen to be involved in breaking its own rules.
Italy and Albania (1923)
The border between Italy and Albania was far from clear and the Treaty of Versailles had never really addressed this issue. It was a constant source of irritation between both nations.
In 1923, a mixed nationality survey team was sent out to settle the issue. Whilst travelling to the disputed area, the Italian section of the survey team, became separated from the main party. The five Italians were shot by gunmen who had been in hiding.
Italy accused Greece of planning the whole incident and demanded payment of a large fine. Greece refused to pay up. In response, the Italians sent its navy to the Greek island of Corfu and bombarded the coastline. Greece appealed to the League for help but Italy, lead by Benito Mussolini, persuaded the League via the Conference of Ambassadors, to fine Greece 50 million lire.
To follow up this success, Mussolini invited the Yugoslavian government to discuss ownership of Fiume. The Treaty of Versailles had given Fiume to Yugoslavia but with the evidence of a bombarded Corfu, the Yugoslavs handed over the port to Italy with little argument
The social successes of the League of Nations
At a social level the League did have success and most of this is easily forgotten with its failure at a political level. Many of the groups that work for the United Nations now, grew out of what was established by the League. Teams were sent to the Third World to dig fresh water wells, the Health Organisation started a campaign to wipe out leprosy. This idea - of wiping out from the world a disease - was taken up by the United Nations with its smallpox campaign.
Work was done in the Third World to improve the status of women there and child slave labour was also targeted. Drug addiction and drug smuggling were also attacked.
These problems are still with us in the C21st - so it would be wrong to criticise the League for failing to eradicate them. If we cannot do this now, the League had a far more difficult task then with more limited resources.
The greatest success the League had involving these social issues, was simply informing the world at large that these problems did exist and that they should be tackled. No organisation had done this before the League. These social problems may have continued but the fact that they were now being actively investigated by the League and were then taken onboard by the United Nations must be viewed as a success.

Sources:

http://www.johndclare.net/league_of_nations4.htm
http://www.indiana.edu/~league/1925.htm
http://www.historylearningsite.co.uk/leagueofnations.htm
http://books.google.ca/books?id=Ylz4fe7757cC&pg=PA154&dq=bulgaria+1925&hl=en&ei=x-wDTNavO4rQMtrV7Ts&sa=X&oi=book_result&ct=result&resnum=10&ved=0CFIQ6AEwCQ#v=onepage&q=bulgaria%201925&f=false
http://avalon.law.yale.edu/20th_century/leagcov.asp