Children were sent to work and given many different jobs such as working on machines, coal mining/breaking up the coal, chimney sweeps because the children were smaller than adults and could fit through. As well as selling newspapers.
Other common jobs (for adults specifically) were spinning jenny and mule, or weaving equipment.
The 54th Massachusetts Volunteer Infantry Regiment is best known for its service leading the failed Union assault on Battery Wagner, a Confederate earthwork fortification on Morris Island,