During the late 1840s, no person stood higher in the public estimation than John Charles Frémont. He led several federal exploratory expeditions into the Rocky Mountains, and the maps and charts made by the expedition members became the standard for those who followed the Oregon and California trails. When the Civil War began, Frémont was also fortunate in that his wife, Jessie Benton Frémont, was extremely well connected to the East Coast establishment. There were those, in 1861, who believed Frémont would become the outstanding military hero of the war.

Frémont had a dictatorial style, however, and he stumbled badly when he declared martial law in Missouri. Not only did he assume all sorts of powers in St. Louis, but Frémont declared—without asking Lincoln or anyone else—that all slaves used by the Confederacy in fighting or building fortifications were now and forever free. To our modern ears, this sounds quite wonderful, but Frémont clearly exceeded his authority, and Lincoln—who was ever conscious of the delicacy of the Border States—had to step in to countermand Frémont’s order. Abolitionists, naturally, hailed Frémont, but by the end of 1861 he was in very bad shape politically and militarily.