April 12, 1861 : Fort Sumter, South Carolina, is attacked by Confederate troops. President Abraham Lincoln issues call for seventy-five thousand volunteers.

April 23, 1861 : Grant rejoins the army as a volunteer.

June 17, 1861 : Grant is appointed colonel of the Twenty-first Illinois Regiment of Volunteers.

September 1861: Grant establishes headquarters in Cairo, Illinois, in command of the District of Southern Illinois and Southeastern Missouri. He occupies Paducah, Kentucky, giving the Union a strong western foothold.

November 7, 1861 : Grant confronts a Confederate force at Belmont, Missouri, scattering his opponents and then withdrawing.

February 1862: Grant captures Fort Henry on the Cumberland River. He leads forces that capture Fort Donelson on the Tennessee River —the first major Union victory of the war. His correspondence to Confederate general Simon Bolivar Buckner—"No terms except an unconditional and immediate surrender can be accepted"—earns him the nickname "Unconditional...