Clara Louise Maass (June 28, 1876 – August 24, 1901) was an American nurse who died as a result of volunteering for medical experiments to study yellow fever. Early life Clara Maass was born in East Orange, New Jersey, to German immigrants Hedwig and Robert Maass. She was the oldest of nine children in a devout Lutheran family. Clara's family was impoverished and to help alleviate the financial burden of one child on her family, she went to work as a "mother's helper" for a local woman while in elementary school. She did not generate any income, but was able to live and eat with her employer's family. In 1895, she became one of the first graduates of Newark German Hospital's Christina Trefz Training School for Nurses. By 1898, she had been promoted to head nurse at Newark German Hospital, where she was known for her hard work and dedication to her profession. Army service In April 1898, during the Spanish–American War, Maass volunteered as a contract nurse for the United States Army (the Army Nurse Corps did not yet exist). She served with the Seventh U.S. Army Corps from October 1, 1898, to February 5, 1899, in Jacksonville, Florida; Savannah, Georgia; and Santiago, Cuba. She was discharged in 1899, but volunteered again to serve with the Eighth U.S. Army Corps in the Philippines from November 1899 to mid-1900. During her service with the military, she saw few battle injuries. Instead, most of her nursing duties came in providing medical aid to soldiers suffering from infectious diseases like typhoid, malaria, dengue and yellow fever. She contracted dengue in Manila, and was sent home. Yellow fever studies Shortly after finishing her second assignment with the army, Maass returned to Cuba in October 1900 after being summoned by William Gorgas, who was working with the U.S. Army's Yellow Fever Commission. The commission, headed by Major Walter Reed, was established during the post-war occupation of Cuba in order to investigate yellow fever, which was endemic in Cuba. One of the commission's goals was to determine how the disease was spread: by mosquito bites or by contact with contaminated objects. The commission recruited human subjects because they did not know of any animals that could contract yellow fever. In the first recorded instance of informed consent in human experiments, volunteers were told that participation in the studies might cause their deaths. As an incentive,