Peace and War: International Relations Timeline 1900-1939

Peace and WarThis timeline details the main events covered in the first 40 years of the twentieth century, including World War One and the Inter War Years, and is linked to the GCSE topic Peace and War: International Relations 1900 – 1939


1879 (7th October)
The Dual Alliance
This was an alliance made between Germany and Austria-Hungary to protect themselves from Russia. The Treaty was instigated by the the German minister Bismarck who was concerned by the fact that relations between Austria-Hungary and Russia had become strained because Russia had attacked Turkey. The terms of the treaty agreed that they would come to the other’s aid in the face of attack by Russia.
1882 (20th May)
The Triple Alliance
This alliance extended the Dual Alliance made in 1879 to include Italy. The Italians had been prompted to join the Alliance because of anger at France’s seizure of Tunisia but also out of a need for protection in case of attack.
1894 (4th January)
The Franco-Russian Alliance
This was a mutual aid alliance between France and Russia. The French Republic had so far remained independent but in the face of the Triple Alliance made the alliance with Russia to curb German and Austro-Hungarian power. In the event of war Germany and Austria-Hungary would be forced to fight a war on two fronts.
1900 (14th June)
German Naval Law
A law was passed in Germany to significantly increase its navy. This alarmed Britain because Britain had always had the largest navy in the world. As a result Britain increased production of battleships to retain its superior position.
1904 (8th February)
Russo-Japanese War
War broke out between Russia and Japanese over control in China.
1904 (8th April)
Entente Cordiale
This was an agreement, but not a formal alliance, between France and Britain. The agreement ended the traditional hostility between the two countries. France recognised British control of Egypt while Britain recognised French control of Morocco, disputes over fishing rights were settled and disputes in Siam (Thailand) were also settled.
1905 (March) to 1906 (May)
First Moroccan Crisis
Morocco wanted independence from France. Germany declared support for the Moroccans against the French. War was avoided following negotiations which allowed France to retain possession of Morocco.
1906 (during)
Britain began a programme of shipbuilding and launched HMS Dreadnought a much more superior battleship than anything existing.
1907 (31st August)
Triple Entente
The signing of the Anglo-Russian Entente together with the Entente Cordiale between Britain and France and the Franco-Russian Alliance created what was known as the Triple Entente and provided for mutual aid guarantees if any country were attacked.
1908 (March) to 1909 (May)
Bosnian Crisis
Austria took control of Bosnia angering Serbia. Serbia threatened Austria-Hungary with war. Russia, allied to Serbia, mobilised its forces. Germany mobilised its forces and threatened Russia. War was avoided when Russia backed down.
1908 (Summer)
General Conrad, Chief of Staff of the Austrian army, reported that there was growing unrest in the Balkans and that Austria Hungary should strongly assert its authority over the region.
1909 (during)
There was a feeling in Britain that Germany was increasing its military resources in order to destroy the British Empire.
1911 (Spring)
A revolt broke out in Morocco which confined the Sultan to his palace. A sizeable number of French troops were moved to Morocco in support of the Sultan.
1911 (1st July)
Second Morocco Crisis
Germany sent a gunboat to the Moroccon port of Agadir in protest at France’s increasing military presence in Morocco. Britain announced that she would stand behind France which threatened to result in the outbreak of war. War was avoided when, in November, Germany agreed to French possession of Morocco in return for some land in the Congo.
1912 (21st May)
German Naval Law
An amendment to the German Naval law was passed approving a new surge in the production of German naval vessels.
1912 (8th October)
The First Balkan War
Serbia, Greece, Montenegro and Bulgaria had formed the Balkan League in order to force the Turks out of the area. On 8th October the Balkan League attacked the Turks and forced them out of the Balkan region. Austria Hungary was alarmed at the prospect of Serbia gaining control and wanted to send troops against Serbia. However, the Great Powers forced a peace settlement on the Balkan States.
1913 (30th May)
The Treaty of London
This Treaty gave additional territory to Serbia but prevented them from having a coastline by creating Albania. Serbia doubled in size and its population increased by 1.6 million to 4.5 million. Serbia gained the backing of Russia which made the country stronger but also made Austria Hungary determined to prevent them becoming even more powerful.
1913 (June)
The Balkan League
The League fell apart when Bulgaria, which had also gained land from the Treaty of London, attacked Greece and Serbia. Full scale war was averted when Russia and Britain intervened and forced them to agree peace.
1913 (August)
Treaty of Bucharest
Bulgaria lost most of the territory gained from the Treaty of London 1913 and wanted revenge on Serbia and Greece. Bulgaria was supported by Austria Hungary.
1914 (May)
Prominent Serbian Military men armed and trained three Bosnian students, Gavrilo Princip, Nedeljko Cabrinovic and Trifko Grabez, in explosives. They were then smuggled back to Bosnia. Their mission was to assassinate the archduke of Austria-Hungary.
1914 (28th June)
Assassination of Franz Ferdinand
The heir to the Austro-Hungarian Empire, Archduke Franz Ferdinand and his wife Sophie were assassinated. The couple were on a visit to the Bosnian capital Sarajevo when they were shot and killed by Gavrilo Princip, a member of the Black Hand Serbian terrorist group.
1914 (after 28th June)
The Austrian government laid the blame for the assassination on Serbia but refrained from declaring war because Serbia was allied to Russia.
1914 (5th July)
Kaiser Wilhelm agreed German support for Austria against Serbia.
1914 (23rd July)
The Austrian government issued an ultimatum to Serbia.
1914 (25th July)
Serbia rejected Austria’s ultimatum.
1914 (28th July)
Austria-Hungary declared war on Serbia
1914 (30th July)
Russia mobilised its army.
1914 (31st July)
Germany issued an ultimatum to Russia to request a halt to mobilisation and an ultimatum to France requesting neutrality in the event of a German-Russian war.
1914 (1st August)
Having no reply to their ultimatum, Germany declared war on Russia and mobilised its army.
1914 (1st August)
France rejected the German ultimatum and mobilised its army.
1914 (2nd August)
Germany invaded Luxembourg. A request to allow German troops to pass through Belgium was denied.
1914 (3rd August)
Germany declared war on France and invaded Belgium following the plan for attacking France outlined by General Schlieffen in 1905.
1914 (4th August)
Britain issued an ultimatum to Germany to remove its troops from Belgium by midnight. Germany did not comply and Britain declared war on Germany for violating Belgian neutrality
1914 (6th August)
Austria declared war on Russia.
1914 (12th August)
Britain and France declared war on Austria.
1914 (13th August)
Japan, allied to Britain, declared war on Germany
1914 (29th October)
Turkey formed an alliance with Germany and Austria-Hungary
1914 (2nd November)
Russia declared war on Turkey
1914 (5th November)
Britain and France declared war on Turkey
1915 (26th April)
Italy changed sides and joined the allies.
1915 (23rd May)
Italy declared war on Germany.
1917 (6th April)
The United states declared war on Germany.
1917 (7th December)
The United States declared war on Austria-Hungary.
1918 (3rd March)
Treaty of Brest-Litovsk
This was a peace treaty negotiated by Russia with Germany. As part of the settlement Germany gained land in Russia.
1918 (8th August)
The allies forced the German army to retreat.
1918 (28th September)
Germany’s ally, Bulgaria, surrendered.
1918 (30th October)
Germany’s ally, Turkey, signed an armistice.
1918 (late October)
German sailors at Kiel mutinied hoping to emulate the Russian Revolution and remove the Kaiser.
1918 (3rd November)
Germany’s ally, Austria-Hungary, signed an armistice.
1918 (9th November)
Kaiser Wilhelm abdicated the German throne.
1918 (11th November)
The Armistice was signed in a carriage of Marshall Foch’s private train in Compiegne, France.
1919 (January)
Paris Peace Conference
Lloyd George of Britain, Georges Clemenceau of France and Woodrow Wilson were the leading delegates of ten from USA, Britain, France, Italy and Japan that met to discuss the peace settlement in Paris. Wilson put forward a 14 point plan that he believed would ensure ongoing peace in Europe. However, Clemenceau wanted to see Germany punished and weakened. Lloyd George, who had recently fought an election promising the British people that Germany would pay, did not want to antagonise the electorate. Although Lloyd George wanted a mid way between Clemenceau and Wilson he sided with France to appease the British electorate.
1919 (28th June)
The Treaty of Versailles Signed
This treaty which dealt with the punishment of Germany contained 440 articles and came into effect in January 1920. Germany had not been invited to the negotiations and even though they felt the terms excessively harsh they had no choice but to sign. Failure to sign may have meant a return to a war that Germany could not win.
The main clauses of the treaty were:
War Guilt Clause – Germany had to accept the blame for the war
Reparations – Germany was to pay £6,600 million in reparations
Army – reduced to 100,000 men
Navy – reduced to 15,000 sailors, 6 battleships, 30 other ships and no submarines
Airforce – destroyed
Land – Germany lost 13% of its territory including the industrial region of Alsace Lorraine. All overseas colonies were re-distributed.
1919 (10th September)
The Treaty of St Germain Signed
This treaty dealt with the punishment of Austria. The main clauses of the treaty were:
Reparations – Austria was to pay reparations but before the amount was set Austria became bankrupt
Army – reduced to 30,000 men
Land – Austria lost land to Czechoslovakia, Italy and Yugoslavia
Anschluss – Union with Germany, was forbidden.
1919 (27th November)
The Treaty of Neuilly Signed
This treaty dealt with the punishment of Bulgaria. The main clauses of the treaty were:
Reparations – Bulgaria had to pay £90 million in reparations
Army – reduced to 20,000 men
Land – Bulgaria lost land to Greece, Romania and Yugoslavia
1920 (10th January)
The League of Nations came into being. The main aim of the League was to maintain World peace. Countries that joined the League agreed to settle international disputes by peaceful means such as placing trade restrictions on aggressor countries. War was to be a last resort but as the League did not have its own army this would be problematic. The League also wanted to work towards a multi-national disarmament reducing arms ‘to the lowest point consistent with national safety’. Germany and its allies were not allowed to joint the League. Russia was also barred from membership because the allies disliked Bolshevism. The United States decided against joining preferring to follow a policy of isolationism rather than becoming involved in the affairs of other countries.
1920 (February)
Yugoslavia invaded Albania. The League of Nations became involved and secured the withdrawal of Yugoslav troops.
1920 (4th June)
The Treaty of Trianon Signed
This treaty dealt with the punishment of Hungary. The main clauses of the treaty were:
Reparations – Hungary was to pay reparations but the amount was never set
Army – reduced to 35,000 men
Land – Hungary lost about 65% of its land to Austria, Czechoslovakia, Romania and Yugoslavia.
1920 (10th August)
Treaty of Sevres
This treaty dealt with the punishment of Turkey. However, Turkey refused to accept the treaty and was particularly upset by the fact that land would be given to Greece. This led to conflict with Greece and allied forces in Turkey were also threatened.
1920 (7th October)
The League of Nations intervened in a dispute between Lithuania and Poland over the city of Vilnius which had a majority Polish population. The League called on Poland to withdraw from the city but instead the Polish sent more troops and took the city on 9th October. The League had no power and was unable to prevent this action.
1921 (during)
Finland and Sweden became involved in a dispute over the Aaland Islands. The League of Nations settled the dispute by giving the islands to Finland but granting the Swedish population of the islands protected minority status.
1921 (during)
Germany and Poland became involved in a dispute over Upper Silesia. The League of Nations settled the dispute by re-drawing the borders according to national determination.
1922 (May)
It was accepted that Germany was unable to pay the reparations payments and they were postponed.
1923 (January)
Lithuania invaded the port city of Memel. Although the city had a majority German population the League had no power to stop the Lithuanian annexation.
1923 (11th January)
60,000 French and Belgian troops occupied the German industrial region the Ruhr. The French felt that as Germany could not pay the reparations they should be able to take German goods as payment instead. This action caused the German economy to collapse.
1923 (24th July)
Treaty of Lausanne
This treaty was negotiated with Turkey to replace the Treaty of Sevres, August 1920.
1923 (August)
Five Italians working on border problems between Greece and Albania were murdered. Italy demanded compensation from Greece and when the Greeks refused to pay Mussolini ordered Italian forces to occupy Corfu. Greece asked for help from the League of Nations but Mussolini was unhappy with the League’s involvement. Nevertheless the matter was decided in Italy’s favour and once compensation had been paid Italy withdrew from Corfu.
1923 (November)
The German economy was in hyperinflation after the German government had printed more money to try to overcome the economic downturn.
1923 (late)
The German Chancellor, Stresemann, introduced a new currency, the deutschmark, to replace the mark. This action stopped the hyperinflation.
1924 (August)
The Dawes Plan
This was an attempt to relieve tensions caused by the reparations Germany had to pay as a result of the Treaty of Versailles. The main points of the plan were:
Following a two year moratorium, Germany would pay reparations at a fixed rate
French and Belgian troops were to evacuate the Ruhr
Germany would be given a loan by the USA and Britain.
1925 (October)
The League of Nations settled a border dispute between Bulgaria and Greece.
1925 (1st December)
Locarno Pact
This was a new agreement designed to reduce tension between France and Germany. It agreed:
The borders between Germany and France were fixed and Alsace Lorraine would be permanently French
The Rhineland area should be de-militarised.
1925 (16th December)
The League of Nations ruled that Mosul was a part of the British mandate of Mesopotamia (Iraq) not Turkey.
1926 (during)
Germany was allowed to join the League of Nations.
1928 (27th August)
Kellogg-Briand Pact
The initial aim of this pact was to improve relations between France and the USA but it was then extended to other countries. Signatories of the pact agreed not to use war to resolve disputes.
1929 (October)
Wall Street Crash
The American stock market crashed causing a World depression as Americans called in international loans. Banks collapsed leaving people with very little money. This meant consumer spending fell and as a result businesses and factories had to cut production and lay off staff. It became known as the Great Depression.
1931 (September)
Japanese forces invaded Manchuria
Japan had been badly affected by the Depression as demand for Japanese goods fell worldwide. Without income from exports Japan could not import goods needed. Manchuria in China was rich in raw materials and also offered additional living space for the Japanese people. China appealed to the League of Nations who requested Japanese withdrawal of troops from the area. The Japanese refused and the League set up a commission to investigate the affair. By the time the investigation was completed in September 1932 Japan had completed its conquest. In February 1933 The League of Nations called for Japan to return Manchuria to China, Japan refused and left the League of Nations. Britain and the USA had territories in the Far East and were reluctant to intervene for fear of Japanese reprisals.
1932 (during)
Disarmament Conference
Delegates from 60 nations met to discuss ways in which to achieve disarmament. The conference failed due to the fact that France and Germany could not agree.
1933 (January)
Adolf Hitler became Chancellor of Germany.
1934 (during)
Adolf Hitler began to build up the German armed forces.
1935 (during)
Hitler held a plebiscite in the Saar region that was under control of the League of Nations. The people in the region voted overwhelmingly to remain German.
1935 (16th March)
Hitler introduced conscription in Germany.
1935 (October)
Italian dictator Mussolini sent 400,000 troops into Abyssinia (modern day Ethiopia). Using modern weapons the Italians defeated the Abyssinians by May 1936 and drove the Emperor Haile Selassie out of the country. Although the League of Nations condemned the Italians and imposed economic sanctions neither had much effect and the League abandoned sanctions in July 1936.
1936 (7th March)
Germany re-occupied the Rhineland. France protested and asked for British support against Hitler, but the British were reluctant to get involved believing Germany to be simply taking what was theirs anyway.
1936 (1st November)
Rome-Berlin Axis
Germany and Italy signed an agreement where they agreed to work together on matters of mutual interest.
1936 (25th November)
Anti-Comintern Pact
This was an anti-communist pact signed by Germany and Japan.
1938 (12th March)
German troops marched into Austria and the two countries were joined together. Britain and France protested but as they were both following a policy of appeasement they did nothing.
1938 (April)
Sudetenland Crisis
Hitler ordered the leader of the Sudeten Nazi Party to stir up trouble in the region. German newspapers then reported that Czech officials were being hostile towards Germans living in the Sudeten region of Czechoslovakia.
1938 (15th September)
Sudetenland Crisis
Hitler demanded that the Sudeten region of Czechoslovakia, which had a majority German population, be given to Germany. He made it clear that he would declare war if the land was not returned.
1938 (22nd September)
Sudetenland Crisis
Hitler now demanded that land in the Sudeten should also be given to Poland and Hungary since there were nationals from both countries living there.
1938 (30th September)
Munich Conference
In a bid to stop Hitler invading the Sudetenland region Chamberlain, Daladier, Mussolini and Hitler met to try to prevent an outbreak of war. The Czech Prime Minister was not invited to attend. Hitler insisted that if he was allowed to have the Sudetenland region of Czechoslovakia then it would be the end of his expansion ideas. It was also agreed that Poland and Hungary would also receive land from the Sudeten. The four leaders agreed to guarantee Czechoslovakia’s new borders.
1938 (30th September)
Chamberlain met with Hitler and an agreement was made whereby the two countries would never go to war but would resolve differences through negotiation.
1938 (October)
A by-election was held in Oxford City following the death of the Conservative MP. Although the Conservatives won the election the opposition anti-appeasement party received a large number of votes.
1938 (9th November)
This was a night of violence towards the Jewish population in Germany where shop windows were smashed, houses and synagogues destroyed. The violence was condemned by Britain.
1939 (15th March)
Hitler sent his troops into Czechoslovakia. He occupied Bohemia and set up a protectorate over Slovakia.
1939 (17th March)
Chamberlain gave a speech stating that Hitler could not be trusted effectively ending the policy of appeasement.
1939 (23rd March)
Hitler sent troops into the Lithuanian city of Memel and reclaimed it for Germany.
1939 (31st March)
Chamberlain made a guarantee to Poland that Britain would defend Poland if Germany invaded on condition that Poland mobilised its army and resisted German invasion.
1939 (7th April)
Italy invaded and occupied Albania.
1939 (April)
Britain and France guaranteed the borders of Romania and Greece.
1939 (22nd May)
Pact of Steel
Italy and Germany signed this pact of friendship and military alliance.
1939 (mid August)
Negotiations for an alliance between Britain and Russia stalled.
1939 (23rd August)
Molotov-Ribbentrop Pact
This was a German Soviet non-aggression agreement where both countries agreed:
Not to support any country making an attack on Russia or Germany
Not to join any alliance that was unfavourable to the other country
To jointly invade Poland and split the region between the two countries.
That Russia could invade and occupy Estonia, Latvia and LIthuania.
1939 (1st September)
German troops invaded Poland. Polish forces fought back but were no match for Hitler’s Blitzkrieg attack.
1939 (3rd September)
At 9am Britain and France issued an ultimatum to Germany demanding that they withdraw troops from Poland. Germany had until 11am to comply. Germany did not comply and Britain and France declared war on Germany.


Published Aug 10, 2017 @ 1:06 pm – Updated – [last-modified]

Harvard Reference for this page:

Heather Y Wheeler. (2017 – 2020). Peace and War: International Relations 1900 – 1939. Available: Last accessed [date]


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