Battle Cry of Freedom: The Civil War Era

by James M. McPherson

The Union army’s capacity to carry on even that one war was threatened by an aspect of the Trent crisis unknown to the public and rarely mentioned by historians. In 1861, British India was the Union’s source of saltpeter, the principal ingredient of gunpowder. The war had drawn down saltpeter stockpiles to the danger point. In the fall of 1861 Seward sent a member of the du Pont company to England on a secret mission to buy all available supplies of saltpeter there and on the way from India. The agent did so, and was loading five ships with 2,300 tons of the mineral when news of the Trent reached London. The government clamped an embargo on all shipments to the United States until the crisis was resolved. No settlement, no saltpeter.