the Klaipėda Region. Germany and Slovakia sign the Schutzzonenvertrag zwischen Deutschland und Slowakei [Treaty on the protective relationship between Germany and the Slovak State], creating the German Zone of Protection in Slovakia. The Slovak–Hungarian War begins. March 31 The United Kingdom and France offer a guarantee of Polish independence. The Slovak–Hungarian War ends. April 1 The Spanish Civil War ends in Nationalist victory. Spain becomes a dictatorship with Francisco Franco as the head of the new government. April 3 Hitler orders the German military to start planning for Fall Weiss, the codename for the attack on Poland, planned to be launched on August 25, 1939. April 4 Hungary and Slovakia sign the Budapest Treaty, handing over a strip of eastern Slovak territory to Hungary. April 7–12 Italy invades Albania with little in the way of military resistance. Albania is later made part of Italy through a personal union of the Italian and Albanian crown. April 14 U.S. President Roosevelt sends letter to German Chancellor Hitler and Italian Prime Minister Mussolini seeking peace. April 18 The Soviet Union proposes a tripartite alliance with the United Kingdom and France. It is rejected. April 28 In a speech before the Reichstag, Hitler renounces the Anglo-German Naval Agreement and the German–Polish declaration of non-aggression May 11 Soviet–Japanese border conflicts: The Battle of Khalkhin Gol begins with Japan and Manchukuo against the Soviet Union and Mongolia. The battle ends in Soviet victory on September 16, influencing the Japanese not to seek further conflict with the Soviets, but to turn towards the Pacific holdings of the Euro-American powers instead. May 17 Sweden, Norway, and Finland reject Germany's offer of non-aggression pacts. May 22 The Pact of Steel, known formally as the "Pact of Friendship and Alliance between Germany and Italy", is signed by Fascist Italy and Nazi Germany. The Pact declares further cooperation between the two powers, but in a secret supplement the Pact is detailed as a military alliance. June 7 The German–Estonian and the German–Latvian non-aggression pacts are concluded. They will remain in force for ten years. June 14 The Tientsin incident occurs, in which the Japanese blockade the British concession in the North China Treaty Port of Tientsin, now called Tianjin. July 10 Prime Minister Neville Chamberlain reaffirms support for Poland and makes it clear that Britain did not view Free City of Danzig as being an internal German-Polish affair and would intervene