Based on the article why were slaves important to the confederate army

Slaves were important to confederate armies because enslaved men were sometimes forced into service to build Confederate fortifications, women to serve as laundresses or cooks for troops in the field. At least partly out of fear that they might lose their freedom if they failed to contribute to the war effort, free blacks often worked beside the slaves, for minimal wages.

.elections are held to determine who serves in congress.