It was very, very important for women to start working during the war because so many people were deployed that the demand for jobs in factories and other places was far higher than there were people available. Also, there were not enough women in the workforce at that time to fill those open positions. They filled many jobs in making supplies for war (that would normally be filled by men). Initially it was difficult to recruit the women (who were originally fitting the bill of "housewives"), and this is where those "We Can Do It" signs with "Rosie the Riveter" came about.
