Charity Adams was just walking down the street one day when she saw a "We want you" poster and was inspired. A few days later she joined the US. Army.
She met Francis and Gretchen during sign in. Over the course of the movie the girls become close friends and depend on each other to keep up motivation through rough times.
The women's battalion (or WACs) practiced drills day and night. They worked incredibly hard to be seen as 'good enough' by the other generals and officers in the Army. However most men didn't think that women should be in the Army. Their ridicule only forced the WACs to work harder.
Dispite all of their hard work most of the African American WACs were assigned degrading tasks that were way under their capability. Charity, Gretchen and Francis were assigned to work in the kitchens despite all being talented officers.
The WACs were enraged, so they decided to take their case to court. Charity won her case and she and her group were transferred to another, better Army base.
The New Army base was bigger and better than the one before but the best jobs were yet to come.