On 1 September 1939, Germany invaded western Poland under the pretext of having been denied claims to the Free City of Danzig and the right to extraterritorial roads across the Polish Corridor, which Germany had ceded under the Versailles Treaty.
The Polish counter offensive to the west halted the German advance for several days, but it was outflanked and encircled by the Wehrmacht. The Battle of the Bzura fought between 9 and 19 September 1939, It began as a Polish counter-offensive, but ended with German victory, German forces took all of western Poland.
With the financial backing of several Jewish investors, including one of the owners, Abraham Bankier, Schindler signed an informal lease agreement on the factory on 13 November 1939 and formalized the arrangement on 15 January 1940. He renamed it Deutsche Emailwarenfabrik (German Enamelware Factory) or DEF, and it soon became known by the nickname "Emalia". He initially acquired a staff of seven Jewish workers (including Abraham Bankier, who helped him manage the company) and 250 non-Jewish Poles.
On 18 November 1939, during the early months of the Nazi occupation of Poland, Oskar Schindler was first introduced to Stern, who was then working as an accountant for Schindler's fellow Abwehr agent Josef "Sepp" Aue, who had taken over Stern's formerly Jewish-owned place of employment as a Treuhander (trustee). Schindler showed Stern the balance sheet of a company he was thinking of acquiring, an enamelware manufacturer called Rekord Ltd owned by a consortium of Jewish businessmen (including Abraham Bankier) that had filed for bankruptcy earlier that year. Stern advised him that rather than running the company as a trusteeship under the auspices of the Haupttreuhandstelle Ost (Main Trustee Office for the East), he should buy or lease the business directly, as that would give him more freedom from the dictates of the Nazis, including the freedom to hire more Jews.