- May 5
- The Vatican recognizes Francisco Franco's government in Spain.
- General Ludwig Beck, Chief of the German Army's General Staff, submits a memorandum to Hitler opposing Fall Grün (Case Green), the plan for a war with Czechoslovakia, under the grounds that Germany is ill-prepared for the world war likely to result from such an attack.
- May 12 – U.S. Secretary of State Cordell Hull rejects the Soviet Union's offer of a joint defence pact to counter the rise of Nazi Germany.
- May 14 – Chile withdraws from the League of Nations.
- May 17 – Information Please debuts on NBC Radio in the United States.
- May 19 – May Crisis begins when Czechoslovak intelligence receives reports of menacing German military concentrations. (It later appears the reports are false.)
- May 20 – Czechoslovakia orders a partial mobilization of its armed forces along the German border.
- May 21 – Matsuo Toi kills 30 people in a village in Okayama, Japan, in the Tsuyama massacre, the world's worst spree killing by an individual until 1982.
- May 23 – No evidence of German troop movements against Czechoslovakia is found and May Crisis subsides. Germany is, nevertheless, perceived to have backed down in the face of Czechoslovak mobilization and international diplomatic unity but the issue of the future of the Sudetenland is far from resolved.
- May 25
- May 28 – In a conference at the Reich Chancellery, Hitler declares his decision to destroy Czechoslovakia by military force, and orders the immediate mobilization of 96 Wehrmacht divisions.
- May 30 – Hitler issues a revised directive for Fall Grün ("Case Green") - the invasion of Czechoslovakia - to be carried out by 1 October 1938.
- July – The Mauthausen concentration camp is built in Austria.
- July 1 – The South African Press Association is established with offices in Cape Town, Johannesburg, Durban, Bloemfontein and Pretoria.
- July 3
- July 5 – The Non-Intervention Committee reaches an agreement to withdraw all foreign volunteers from the Spanish Civil War. The agreement is respected by most Republican foreign volunteers, notably by those from England and the United States, but is ignored by the governments of Germany and Italy.
- July 6 – The Evian Conference on Refugees is convened in France. No country in Europe is prepared to accept Jews fleeing persecution and the United States will only take 27,370.
- July 14 – Howard Hughes sets a new record by completing a 91-hour airplane flight around the world.
- July 18 – Wrong Way Corrigan takes off from New York, ostensibly heading for California. He lands in Ireland instead.
- July 22 – Britain rejected a proposal from its ambassador in Berlin, Nevile Henderson, for a four power summit on Czechoslovakia consisting of Britain, France, Germany and the U.S.S.R. London would under no circumstances accept the U.S.S.R. as a diplomatic partner.
- July 24 – First ascent of the Eiger north face.
- July 28
- July 30 – The first ever issue of The Beano children's comic is published in Britain.
- August – In the face of overwhelming Japanese military pressure, Chiang Kai-shek withdraws his government to Chungking.
- August 3 – Lord Runciman, sent by Neville Chamberlain, arrives in Prague on his Mission of mediation in the Sudetenland dispute.
- August 10 – At a secret summit with his leading generals, Hitler attacks General Beck's arguments against Fall Grün, winning the majority of his senior officers over to his point of view.
- August 18
- August 23 – Hitler, hosting a dinner on board the ocean liner Patria in Kiel Bay, tells the Regent of Hungary, Admiral Horthy, that action against Czechoslovakia is imminent and that "he who wants to sit at the table must at least help in the kitchen", a reference to Horthy's designs on Carpathian Ruthenia.
- August 27 – General Beck leaves office as Chief of the General Staff; he is replaced by General Franz Halder.
- August 28 – Lord Runciman's mission to mitigate the Sudetenland crisis begins to break down. British Prime Minister Neville Chamberlain recalls the British Ambassador Nevile Henderson from Berlin, to instruct Henderson to set up a personal meeting between Chamberlain and Hitler.
- August 31 – Winston Churchill, still believing France and Britain mean to honor their promises to defend Czechoslovakia against Nazi aggression, suggests in a personal note to Neville Chamberlain that His Majesty's Government may want to set up a broad international alliance including the United States (specifically mentioning U.S. President Franklin D. Roosevelt as possibly receptive to the idea) and the Soviet Union.
- September – The European crisis over German demands for annexation of the Sudeten borderland of Czechoslovakia becomes increasingly severe.
- September 2 – Soviet Ambassador to Britain Ivan Maisky calls on Winston Churchill, telling him that Soviet Foreign Commissar Maxim Litvinov has expressed to the French chargé d'affaires in Moscow that the Soviet Union is willing to fight over the territorial integrity of Czechoslovakia.
- September 4 – During the ceremony marking the unveiling of a plaque at Pointe de Grave, France, celebrating Franco-American friendship; American Ambassador William Bullitt in a speech states, "France and the United States were united in war and peace", leading to much speculation in the press that if war did break out over Czechoslovakia, then the United States would join the war on the Allied side.
- September 5 – Czechoslovakian President Edvard Beneš invites mid-level representatives of the Sudeten Germans to the Hradčany palace, to tell them he will accept whatever demands they care to make, provided the Sudetenland remains part of the Republic of Czechoslovakia.
- September 6 – What eventually proves to be the last of the "Nuremberg Rallies" begins. It draws worldwide attention because it is widely assumed Hitler, in his closing remarks, will signal whether there will be peace with or war over Czechoslovakia.
- September 7 – The Times publishes a lead article which calls on Czechoslovakia to cede the Sudetenland to Germany.
- September 9 – U.S. President Franklin D. Roosevelt disallows the popular interpretation of Bullitt's speech at a press conference at the White House. Roosevelt states it is "100% wrong" the U.S. would join a "stop-Hitler bloc" under any circumstances and makes it quite clear that in the event of German aggression against Czechoslovakia, the U.S. would remain neutral.
- September 10 – Hermann Göring, in a speech at Nuremberg, calls the Czechs a "miserable pygmy race" who are "harassing the human race." That same evening, Edvard Beneš, President of Czechoslovakia, makes a broadcast in which he appeals for calm.
- September 12 – Hitler makes his much-anticipated closing address at Nuremberg, in which he vehemently attacks the Czech people and President Beneš. American news commentator Hans von Kaltenborn begins his famous marathon of broadcast bulletins over the CBS Radio Network with a summation of Hitler's address.
- September 13 – The followers of Konrad Henlein begin an armed revolt against the Czechoslovak government in Sudetenland. Martial law is declared and after much bloodshed on both sides order is temporarily restored. Neville Chamberlain personally sends a telegram to Hitler urgently requesting that they both meet.
- September 15 – Neville Chamberlain arrives in Berchtesgaden to begin negotiations with Hitler over the Sudetenland.
- September 16 – Lord Runciman is recalled to London from Prague in order to brief the British government on the situation in the Sudetenland.
- September 17 – Neville Chamberlain returns temporarily to London to confer with his cabinet. The U.S.S.R. Red Army masses along the Ukrainian frontier. Rumania agrees to allow Soviet soldiers free passage across her territory to defend Czechoslovakia.
- September 18
- During a meeting between Neville Chamberlain, the recently elected Premier of France, Édouard Daladier, and Daladier's Foreign Minister, Georges Bonnet, it becomes apparent neither the British nor the French governments are prepared to go to war over the Sudetenland. The Soviet Union declares it will come to the defence of Czechoslovakia only if France honours her commitment to defend Czechoslovak independence.
- Mussolini makes a speech in Trieste, Italy where he indicates that Italy is supporting Germany in the Sudeten crisis.
- September 21
- In the early hours of the day, representatives of the French and British governments call on Czechoslovak President Edvard Beneš to tell him France and Britain will not fight Hitler if he decides to annex the Sudetenland by force. Late in the afternoon the Czechoslovak government capitulates to the French and British demands.
- Winston Churchill warns of grave consequences to European security if Czechoslovakia is partitioned. The same day, Soviet Foreign Commissar Maxim Litvinov makes a similar statement in the League of Nations.
- The 1938 New England hurricane strikes Long Island and southern New England, killing over 300 along the Rhode Island shoreline and 600 altogether.
- Following the capitulation of the Czech government to Germany's demands, both Poland and Hungary demand slices of Czech territory where their nationals reside.
- September 22
- Unable to survive the previous day's capitulation to the demands of the English and French governments, Czechoslovak premier Milan Hodža resigns. General Jan Syrový takes his place.
- Neville Chamberlain arrives in the city of Bad Godesberg for another round of talks with Hitler over the Sudetenland crisis. Hitler raises his demands to include occupation of all German Sudeten territories by October 1. That night after a telephone conference, Chamberlain reverses himself and advises the Czechoslovaks to mobilize.
- Olsen and Johnson's musical comedy revue Hellzapoppin begins its 3-year run on Broadway.
- September 23
- The Czechoslovak army mobilizes.
- As the Polish army masses along the Czech border, the Soviet Union warns Poland that if it crosses the Czech frontier, Russia will regard the 1932 non-aggression pact between the two countries as void.
- September 24
- Sir Eric Phipps, British Ambassador to France, reports to London, "all that is best in France is against war, almost at any price", being opposed only by a "small, but noisy and corrupt, war group". Phipps's report creates major doubts about the ability and/or willingness of France to go to war.
- At 1:30 AM, Adolf Hitler and Neville Chamberlain conclude their talks on the Sudetenland. Chamberlain agrees to take Hitler's demands, codified in the Godesberg Memorandum, personally to the Czech Government. The Czech Government rejects the demands, as does Chamberlain's own cabinet. The French Government also initially rejects the terms and orders a partial mobilization of the French army.
- September 26 – In a vitriolic speech at Berlin's Sportpalast, Hitler defies the world and implies war with Czechoslovakia will begin at any time.
- September 28 – As his self-imposed October 1 deadline for occupation of the Sudetenland approaches, Adolf Hitler invites Italian Duce Benito Mussolini, French Premier Edourd Deladier and British Prime Minister Neville Chamberlain to one last conference in Munich. The Czechs themselves are not invited.
- September 29
- September 30 – Neville Chamberlain returns to Britain from meeting with Adolf Hitler and declares "Peace for our time".
- October – The Imperial Japanese Army largely overruns Canton.
- October 1 – German troops march into the Sudetenland. The Polish government gives the Czech government an ultimatum stating that Zaolzie region must be handed over within twenty-four hours. The Czechs have little choice but to comply. Polish forces occupy Zaolzie.
- October 2
- October 3 – Production of the Jefferson nickel begins in the United States, replacing the Buffalo nickel (last struck in April). The new nickel is released on November 15.
- October 4 – The Republican forces in the Spanish Civil War begin withdrawing their foreign volunteers from combat as agreed on July 5.
- October 5
- Edvard Beneš, president of Czechoslovakia, resigns.
- Nuremberg Laws In Nazi Germany, Jews' passports are invalidated and those who need a passport for emigration purposes are given one marked with the letter J ("Jude" – "Jew").
- October 10 – The Blue Water Bridge opens, connecting Port Huron, Michigan and Sarnia, Ontario.
- October 16 – Winston Churchill, in a broadcast address to the United States, condemns the Munich Agreement as a defeat and calls upon America and western Europe to prepare for armed resistance against Hitler.
- October 18 – The German government expels 12,000 Polish Jews living in Germany; the Polish government accepts 4,000 and refuses admittance to the remaining 8,000, who are forced to live in the no-man's land on the German-Polish frontier.
- October 21 – In direct contravention of the recently signed Munich Agreement, Adolf Hitler circulates among his high command a secret memorandum stating that they should prepare for the "liquidation of the rest of Czechoslovakia" and the occupation of Memel.
- October 24
- October 27
- DuPont announces a name for its new synthetic yarn: "nylon".
- Jews with Polish citizenship are evicted from Nazi Germany.
- October 30 – Orson Welles' radio adaptation of The War of the Worlds is broadcast, causing panic in various parts of the United States.
- October 31 – Great Depression: In an effort to try restore investor confidence, the New York Stock Exchange unveils a 15-point program aimed to upgrade protection for the investing public.
- November 1 – Horse racing: Seabiscuit defeats War Admiral by four lengths in their famous match race at Pimlico Race Course in Baltimore.
- November 2 – Arising from The Munich Agreement Hungary is "awarded" the Felvidek region of South Slovakia and Ruthenia.
- November 4 – At a public meeting in Epping, Winston Churchill narrowly survives an attempt by fellow Conservative and constituent Sir Colin Thornton-Kemsley to remove him from Parliament.
- November 7 – Ernst vom Rath, the Third Secretary at the German Embassy in Paris, is assassinated by Herschel Grynszpan.
- November 9 – Holocaust – Kristallnacht: In Germany, the "night of broken glass" begins as Nazi activists and sympathizers loot and burn Jewish businesses (the all night affair sees 7,500 Jewish businesses destroyed, 267 synagogues burned, 91 Jews killed and at least 25,000 Jewish men arrested).
- November 10
- November 11 – Celâl Bayar forms the new government of Turkey. (10th government; Celal Bayar had served twice as a prime minister)
- November 12 – French Finance Minister Paul Reynaud brings into effect a series of laws aiming at improving French productivity (thus aiming to undo the economic weaknesses which led to Munich), and undoes most of the economic and social laws of the Popular Front.
- November 16
- Britain formally recognises Italy's control of Ethiopia. In return Mussolini agrees to withdraw 10,000 troops from Spain.
- LSD is first synthesized by Albert Hofmann from ergotamine at the Sandoz Laboratories in Basel.
- The first reported "attack" of the Halifax Slasher mass hysteria incident in England.
- November 18 – Trade union members elect John L. Lewis as the first president of the Congress of Industrial Organizations in the United States.
- November 25 – French Foreign Minister Georges Bonnet informs Léon Noël, the French Ambassador to Poland, that France should find an excuse for terminating the 1921 Franco-Polish alliance.
- November 30
- The Czechoslovak parliament elects Emil Hácha as the new president of Czechoslovakia.
- Benito Mussolini and his Foreign Minister Count Galeazzo Ciano order "spontaneous" demonstrations in the Italian Chamber of Deputies, demanding that France cede Tunisia, Nice, Corsica and French Somaliland to Italy. This begins an acute crisis in Franco-Italian relations that lasts until March 1939.
- Corneliu Zelea Codreanu, leader of the Romanian fascist Iron Guard, is murdered on the orders of King Carol II of Romania. Officially, Codreanu and the 13 other Iron Guard leaders are "shot while trying to escape".
- A general strike is called in France by the French Communist Party to protest the laws of November 12.
беларуская (тарашкевіца): 1938
srpskohrvatski / српскохрватски: 1938