Simplify the following text for a Grade 12 native English-speaking person.
Original: He is credited with saving almost 1,200 Jews during the Holocaust by employing them in his enamelware and ammunitions factories , which were located in what is now Poland and the Czech Republic respectively .
Simplified: He saved almost 1,200 Jews during the Holocaust by making them work his enamelware and ammunitions factories , which were in what is known today as Poland and the Czech Republic .