[142]
Grant had won the first major victory for the Union, capturing Floyd's entire rebel army of more than 12,000. Halleck was angry that Grant had acted without his authorization and complained to McClellan, accusing Grant of "neglect and inefficiency". On March 3, Halleck sent a telegram to Washington complaining that he had no communication with Grant for a week. Three days later, Halleck followed up with a postscript claiming "word has just reached me that ... Grant has resumed his bad habits (of drinking)."[143] Lincoln, regardless, promoted Grant to major general of volunteers and the Northern press treated Grant as a hero. Playing off his initials, they took to calling him "Unconditional Surrender Grant".[144]

Shiloh (1862) and aftermath
Further information: Battle of Shiloh
Battle of ShilohThulstrup 1888Battle of Shiloh map
With great armies now massing, it was widely thought in the North that another western battle might end the war.[145] Grant, reinstated by Halleck at the urging of Lincoln and Secretary of War Edwin Stanton, left Fort Henry and traveled by boat up the Tennessee River to rejoin his army with orders to advance with the Army of the Tennessee into Tennessee. 