At the impressionable age of 15, Clara’s life took a dramatic shift when L. N. Fowler, a noted phrenologist, demanded Barton's parents have her teach school. In 1839, Clara passed her final examination and began her 10 year teaching career in school districts near Oxford, Massachusetts. Her natural ability seemed to flow with whatever she did. As the schools she taught at won prizes in discipline excellence, she was rewarded with new job offers including a premium salary. In 1854, suffering from overload, Clara decided to go on a hiatus from teaching to pursue some refreshment courses of her own. She voyaged to Clinton, New York to the Clinton Liberal Institute where she studied analytic geometry, calculus, astronomy, mathematics, and natural science, as well as French, German, ancient history, philosophy, and religion. When the term was over she was invited to stay with a friend in Hightstown, New Jersey. Delighted by the area, soon after she was teaching in nearby Cedarville school and later in Bordentown. It was in New Jersey, where Clara started the state’s first free public school. The attendance sky rocketed to 600 under Clara’s leadership; however, instead of hiring Clara as head of the school they hired a man. In dismay, she moved to Washington D.C. to begin work as a clerk in the U.S. Patent Office.
Barton resigned her position in the Patent Office once the Civil War started to devote herself to the care of wounded soldiers. In April 1961 she established an agency to obtain and distribute her own medical supplies to wounded soldiers. For close to a year, she passionately lobbied the U.S. Army and in July 1862 was granted permission to travel behind the lines. In 1865, President Abraham Lincoln assigned Barton with the exceptionally challenging task of directing the search for more than 20,000 Union Army men. As the war began to slow, Clara was sent to Andersonville, Georgia to identify and mark the graves of some 13,000 Union soldiers buried there. In 1869, under doctor recommendation Clara took a restful trip to Europe. During a stop in Switzerland, she met Dr. Louis Appia, and, for the first time, heard about the International Red Cross. Unfortunately, the United States had not been a participant in the Geneva Convention of 1864, which made the International Red Cross possible, so Barton didn't learn of its existence until traveling in Europe. While in Europe, she developed a friendship with the Grand Dutchess. With the support of the Grand Dutchess and International Red Cross, in 1870 Barton went to the battlefield and to aid the overwhelmed city of Strasbourg, France. Sadly, in 1873 Clara began to suffer from nervous exhaustion, she returned to the United States and in 1876 she moved to Dansville, New York. Promptly after arriving home, Clara’s work began rallying to have the US join in this treaty; vowing to not only establish an equally successful American Association of the Red Cross in the United States, but vouching to expand on original idea of the Red Cross and coming up with inventive ideas incorporating ways to assist people should any great national disasters occur. This contribution awarded the United States the "Good Samaritan of Nations" label. Barton held the title of President of the American National Red Cross for twenty-two years. Under her leadership, she implemented the framework of the Red Cross to fit the needs of the United States not only during wartime but in peacetime.
Barton was an accomplished educator, hard-working woman, and devote activist who always saw through every project until the end. She had an array of friends including Susan B. Anthony and Lucy Stone whom she enjoyed spending her later years with. Barton herself was notably the most decorated American woman, receiving the Iron Cross, the Cross of Imperial Russia, and the International Red Cross Medal. Her final contribution was founding the National First Aid Society in 1904, which later became part of the American Red Cross. Clara retired from the American Red Cross as President of the organization in 1904 at the age of 83. She quietly returned to Glen Echo, Maryland where she spent her remaining years. Clara Barton passed away on April 12, 1912 in her home due to complications of a cold.