a black man's war," due to the presence of the incoming of thousands of runaway slaves. This marked a sudden shift in the war. In March 1862 Congress passed a law formalizing this policy. By the fall, the Army had built the Great Contraband Camp in Hampton to house the families. It was the first of more than 100 that would be established by war's end, and the Roanoke Island Freedmen's Colony (1863–1867), which started as a contraband camp. Many contrabands were employed by the Union Army in support roles such as cooks, wagon drivers, and laborers. Beginning in January 1863, the United States Colored Troops were formed, with many contrabands enlisting; these units were composed primarily of white officers and African-American enlisted men, and eventually numbered nearly 180,000 soldiers. Mary S. Peake was teaching the children of freedmen to read and write near Fort Monroe. She was the first black teacher hired by the American Missionary Association (AMA), a northern missionary group led by black and white ministers from the Congregational, Presbyterian and Methodist denominations, who strongly supported education of freedmen. Soon she was teaching children during the day and adults at night. The AMA sponsored hundreds of northern teachers and hired local teachers in the south; it founded more than 500 local schools and 11 colleges for freedmen and their children. During the Civil War Fort Monroe was the site of a military balloon camp under the flight direction of aeronaut John LaMountain. The Union Army Balloon Corps was being developed at Fort Corcoran near Arlington under the presidentially appointed Prof. Thaddeus S. C. Lowe. At the same time, LaMountain, who was vying for position as Chief Aeronaut, had gained the confidence of Butler in using his balloon Atlantic for aerial observations. LaMountain is credited with having made the first successful report from an aerial station that was of practical military intelligence. LaMountain was later reassigned to Lowe's balloon corps, but after a period of in-fighting with Lowe, he was released from military service. Lowe eventually assigned regular military balloons to Fort Monroe. In 1861 the prototype 15-inch Rodman gun was delivered to Fort Monroe and was subsequently fired 350 times in testing. This weapon (Fort Pitt Foundry No. 1 of 1861) is displayed at the fort as of 2018; a plaque states that it was test fired for President Lincoln and was nicknamed the "Lincoln gun". This