Annexation of Memelland March 22nd 1939.
4 Lituanian stamps with unofficial overprint.

Quick history:
By late 1938, Lithuania had lost control over the situation in the Territory. In the early hours of 23 March 1939, after an oral ultimatum had caused a Lithuanian delegation to travel to Berlin, the Lithuanian Minister of Foreign Affairs Juozas Urbšys and his German counterpart Joachim von Ribbentrop signed the Treaty of the Cession of the Memel Territory to Germany in exchange for a Lithuanian Free Zone for 99 years in the port of Memel, using the facilities erected in previous years.

When the area was returned to German control in 1939 under Nazi Germany, many Lithuanians and their organizations began leaving Memel and the surrounding area. Memel was quickly turned into a fortified naval base by the Germans. After the failure of the German invasion of the USSR (Operation Barbarossa) in 1941, the fate of East Prussia and Memel was sealed. By October 1944 the inhabitants of the area, without ethnic distinction, had to make a decision whether to stay or leave. Nearly all of the population were evacuated from the approaching Red Army, but the city itself was defended by the German army during the Battle of Memel until January 28, 1945. After its capture only six persons were found in the city.