On 20 March 1939, Nazi Germany's foreign minister Joachim von Ribbentrop presented an oral ultimatum to Juozas Urbšys, foreign minister of Lithuania. Germany demanded that Lithuania give up the Klaipėda Region (also known as the Memel Territory) which had been detached from Germany after World War I, or the Wehrmacht would invade Lithuania and the de facto Lithuanian capital Kaunas would be bombed. The Lithuanians had been expecting the demand after years of rising tension between Lithuania and Germany, increasing pro-Nazi propaganda in the region, and continued German expansion. It was issued just five days after the Nazi occupation of Czechoslovakia. The 1924 Klaipėda Convention had guaranteed the protection of the status quo in the region, but the four signatories to that convention did not offer any material assistance. The United Kingdom and France followed a policy of appeasement, while Italy and Japan openly supported Germany, and Lithuania accepted the ultimatum on 23 March 1939. It proved to be the last territorial acquisition for Germany before World War II, producing a major downturn in Lithuania's economy and escalating pre-war tensions for Europe as a whole.
Klaipėda dispute
Klaipėda (German: Memel), an important seaport in East Prussia, was detached from Germany by Article 28 of the Treaty of Versailles and was governed by the Allies according to Article 99. France assumed administration of the region while Lithuania continued to lobby for its control, claiming that it should belong to Lithuania as it had a significant Lithuanian population (see Lithuania Minor) and was that country's only access to the Baltic Sea. Poland also laid claim to the territory. As the Allies were hesitant to make a decision and it seemed that the region would remain a free state much like the Free City of Danzig, Lithuania took the initiative and organized the Klaipėda Revolt in January 1923. Soviet Russia and Germany supported the action. The region, as an autonomous territory with its own parliament (Klaipėda Parliament), was attached to Lithuania. The region covered about and had a population of approximately 140,000.
During the 1920s, Lithuania and Germany maintained a relatively normal relationship as they were united by anti-Polish sentiment. In January 1928, after long and difficult negotiations, Germany and Lithuania signed a border treaty, which left Klaipėda on the Lithuanian side. However, tensions began rising in the 1930s after Nazi Germany replaced the Weimar Republic. An especially tense period came in February 1934 when the Lithuanian government arrested dozens of pro-Nazi activists. In response to these arrests and trials, Germany declared a boycott of Lithuanian agricultural imports. The boycott caused an economic crisis in Suvalkija (southern Lithuania), where farmers organized violent protests. However, after the plebiscite in Saar most of the pro-Nazi prisoners received amnesty. In the wake of the amnesties, Lithuanian prestige suffered both abroad and in Klaipėda, allowing Germany to strengthen its influence in the region.
Rising tension
In the spring of 1938 Adolf Hitler personally stated that gaining Klaipėda was one of his highest priorities, second only to gaining the Sudetenland. When Poland presented its ultimatum to Lithuania in March 1938, Germany openly declared that in the event of a military clash between Poland and Lithuania, its army would invade Lithuania to capture Klaipėda and a large portion of western Lithuania. A week after Lithuania accepted the Polish ultimatum, Germany presented an eleven-point memorandum that demanded freedom of action for pro-German activists in the region and a lessening of Lithuanian influence there. Its points were worded in a deliberately vague manner, which would enable Germany to accuse Lithuania of violations. Lithuania chose to postpone dealing with the problem, hoping that the international situation would improve. In the meantime it hoped to give the German population no reasons for complaint.