Why was Clara Barton know as the angel of the battlefield during the US Civil war?

Clara Barton is called the angel of the battlefield for many different reasons. She helped soldiers at the front line of battle. She also wrote letters to the family and friends of injured or sick soldiers informing them on their loved one's condition. Clara was also the first one to go to the front lines because she was brave and was not afraid to help others, even if it meant putting her own life on the line. In this way she was like an angel to the soldiers, on the battlefield and off.