On February 26, 1863, President Abraham Lincoln signed the National Banking Act into law, creating the American banking charter system. The Act furthermore created the Office of the Comptroller of Currency (OCC) within the Treasury Department. The law was further intended to help raise money for the Civil War by pressing banks to buy federal as opposed to state bonds. The law was not as successful as intended in this regard and was soon replaced by the National Banking Act of 1864.
Read the history of the OCC from the US Department of the Treasury.