Clara Barton is famous for founding the American Red Cross. Her experiences as a nurse during the Civil War highlighted the need for organized humanitarian efforts, leading her to establish the Red Cross in 1881. Barton's commitment to disaster relief and medical care in times of crisis positioned the organization to serve both in domestic and international emergencies. Her advocacy for providing aid during conflicts established foundational principles for modern humanitarian efforts, making her an icon in the history of social change and humanitarian work.