The stamp was issued to fulfill a need for a reduced rate, 2-Cent denomination for newspaper, magazine, and local deliveries; and was often used to "make up" higher rates, or split in half to make up lower ones (a 1-Cent stamp) due to shortages at the local post office.
During the Civil War, the "Black Jack" was supposed to have been favored by both North and South, but as soon as the South got wind of the North making a stamp depicting one of their own heroes, they printed a 2-Cent stamp of their own in reaction.
After the War was over, poverty forced people to wash off the cancels from the stamps and attempt to use them over again, such that the Government decided to put an antitheft device onto the stamps known as a grill. This grill, which consisted of various rows of tiny indentations into the stamps, was supposed to make it impossible to wash off the cancellations without being detected; but thieves usually got around this by bisecting the stamp, and then reusing that portion that didn't have a cancel on it.
Sources
Scott Publishing Company, 2005 Specialized Catalogue of United States Stamps and Covers (2004)
Lester G. Brookman, The 19th Century Postage Stamps of the United States (1947, vol. I) [exhaustive information about "grills"]
John Kerr Tiffany, History of the Postage Stamps of the United States of America (1887)
