Terry L. Seip, "McCulloch, Hugh," American National Biography Online, February 2000, http://www.anb.org/articles/04/04-00682.html.
As the war began, McCulloch continued to head the Indiana banking system and in 1862 he lobbied against creating a national banking system, which he saw as "greatly prejudicial to the State banks." The following year, however, Congress passed an amended version of the bill, which satisfied McCulloch's objections, and he accepted an invitation from Secretary of the Treasury Salmon P. Chase to become comptroller of the currency for the new system and moved to Washington to organize the National Currency Bureau. Working with Chase and then William Pitt Fessenden when Chase resigned in 1864, McCulloch was instrumental in getting the banking network off to a solid start. When Fessenden resigned in March 1865, McCulloch agreed to Abraham Lincoln's offer of the Treasury portfolio, and he continued under Andrew Johnson's administration.