Defence Volunteers, later known as the Home Guard. May 15 WWII: The Dutch Army formally signs a surrender document. Women's stockings made of nylon are first placed on sale across the United States. Almost five million pairs are bought on this day. May 16 – President of the United States Franklin D. Roosevelt, addressing a joint session of the U.S. Congress, asks for an extraordinary credit of approximately $900,000,000 to finance construction of at least 50,000 airplanes per year. May 17 – WWII: Brussels falls to German forces; the Belgian government flees to Ostend. Zeeland is overrun by German forces, ending the Battle of the Netherlands and beginning full German occupation of the Netherlands (Noord-Beveland surrenders on May 18, and the remaining Dutch troops are withdrawn from Zeelandic Flanders on May 19). May 18 – Marshal Philippe Pétain is named vice-premier of France. May 19 – General Maxime Weygand replaces Maurice Gamelin as commander-in-chief of all French forces. May 20 WWII: German forces (2nd Panzer Division), under General Rudolf Veiel, reach Noyelles on the English Channel. Holocaust: The Nazi concentration camp and extermination camp Auschwitz-Birkenau, the largest of the German concentration camps, opens in occupied Poland, near the town of Oświęcim. From now on until January 1945, around 1.1 million people will be killed here. May 22 – WWII: The Parliament of the United Kingdom passes the Emergency Powers (Defence) Act 1939, giving the government full control over all persons and property. May 24 – WWII: The Anglo-French Supreme War Council decides to withdraw all forces under its control from Norway. Hitler issues Der Halte Befehl, a stop order preventing his Panzer divisions advancing on Dunkirk. May 25 – The Crypt of Civilization time capsule at Oglethorpe University, Brookhaven, Georgia in the United States, is sealed shut, with a projected opening date of 8113 CE. May 26 WWII: The Dunkirk evacuation of the British Expeditionary Force begins. The first free flight of Igor Sikorsky's Vought-Sikorsky VS-300 helicopter is made. May 27 – WWII: Le Paradis massacre: 97 retreating British soldiers of the Royal Norfolk Regiment are executed by German troops of 3rd SS Panzer Division Totenkopf after surrendering in France. May 28 – WWII: King Leopold III of Belgium orders the Belgian forces to cease fighting, ending the 18-day Battle of Belgium. Leaders of the Belgian government on French territory declare Leopold deposed. Land Battle of Narvik: German forces retire,