Schindler employed Jews, initially for economic reasons - they were free labor. Probably the creation of the ghetto and brutal deportation actions made him realize that as a director of a prosperous factory, he had a chance to help those people – the Kennkarten issued to Jewish workers protected them from deportation and transport to camps.
After the liquidation of the ghetto (March 1943), Schindler, thanks to his contacts and bribes, obtained permission to set up a sub-camp of the Płaszów labor camp on the factory premises. Its workers lived in barracks built near the factory, away from the sadistic camp commandant Amon Goeth and his guards. The factory became a safe shelter for about 1000 people, including the elderly, the sick, and children, where sanitary conditions and food rations were much better than in the camp.
When the Nazis started to prepare for evacuation in the face of the defeat of the war, the sub-camp in Emalia was liquidated. Schindler then started an ammunition factory in Brünnlitz (Czech Republic) and employed "his" Jews there. In doing so, he saved the lives of approximately 1,100 people.
For more information about Oskar Schindler’s Enamel Factory click here - Oskar Schindler's Enamel Factory
Source: Poland Daily 24, muzeumkrakowa.pl, krakow.travel