Unfortunately, the president with whom Grant spent far more time, Andrew Johnson, taught negative lessons. Lincoln did not conceal a vein of coarseness, but Johnson displayed it proudly. By emphasizing his humble origins and rise to prominence through his own efforts, Johnson may have seemed reminiscent of Grant's father, whom, not incidentally, Johnson appointed postmaster of Covington, Kentucky, in an embarrassingly blatant attempt to obligate his son.
Johnson and Grant headed toward a collision over policy. Both men had owned slaves before the Civil War, but Johnson had gloried in his ownership, had once declared his dream that every American family might own one, and based policy upon his firm conviction in the superiority of whites. Grant had worked Hardscrabble with slaves supplied by his father-in-law, and Julia continued to own slaves during the Civil War; but Grant freed one slave he owned himself in 1859, at a time when he desperately needed the money that sale of a slave could bring. At the onset of the Civil War, he dreaded a slave insurrection, which he assumed would have to be suppressed by the armed force of both North and South.
Just as he changed from Democrat to Republican during the Civil War, his attitude toward blacks shifted. From the earliest days of the Civil War, blacks contributed to a Union victory as they flocked through northern lines bringing information of southern strength and plans. Once within the lines, they gratefully accepted employment in support of the army, working at tasks that released white men for combat. Grant saw the first black troops in his army prove their capacity as soldiers by their defense of Millikens' Bend in June 1863. By the close of the Civil War, 10–12 percent of the Union army consisted of black troops; an important component of the armies, they had proved themselves on many battle-fields.
Thus, Grant, the last former slaveholder elected president, was forced by his military role to consider blacks both as human beings and as soldiers. If he did not transcend the racism of his day, as commanding general he assumed responsibility for all men who served in the army, white and black. Like Lincoln, he believed that governmental responsibility extended to veterans; denying civil rights and citizenship to men who had fought offended his sense of duty. Yet Grant shared some of Johnson's sympathy with the whites of the South: after all, he had firm friendships with many southern officers of the old army, had married a southerner (a cousin of the Confederate general James Longstreet), and had never participated in the bitter sectional debate before the Civil War.
Johnson, appointed brigadier general at the time he was named military governor of Tennessee, had really served in a civil capacity. Ever the politician, Johnson tried to manipulate the army to serve his goals both in Tennessee and in the White House. Sent on a tour of inspection of the South by Johnson, Grant returned with a report that emphasized the willingness of southerners to reaffirm their allegiance, a view that suited Johnson, but did not recommend withdrawal of troops or elimination of the Freedmen's Bureau, an agency established to care for, and protect, former slaves.
Johnson's policy of rapid restoration of political rights in former Confederate states exposed Union soldiers to suits filed in state courts by their former enemies. Grant issued orders in January 1866, authorizing removal of such cases to federal courts or to those of the Freedmen's Bureau. Johnson soon embarked on open warfare with Congress, which passed the Freedmen's Bureau bill and the civil rights bill over his vetoes. Johnson and Grant soon found themselves in quiet conflict over the enforcement of congressional legislation by the army.
The conflict remained quiet because Grant, as a soldier, was determined to obey the commander in chief and because Johnson needed Grant's popularity to shore up his political power. Johnson dragged Grant along on a "swing around the circle," a trip ostensibly to dedicate the Douglas tomb in Chicago but really a political tour to allow Johnson to argue before the voters his case against congressional Radicals, who demanded sweeping political and social change in the South. Johnson's undignified harangues disgusted Grant, who temporarily left the party at Cleveland, leading staunch supporters of Johnson to charge that Grant had withdrawn to recover from excessive drinking. Recognizing the dangers of their eroding relationship, Johnson tried to send Grant on a mission to Mexico and to bring William T. Sherman to Washington in his place; Grant flatly refused to go, insisting that the president had no authority to order an officer on a civilian mission.
Congressional Republicans took advantage of the estrangement through the first Reconstruction Act, whereby they established five military districts in the former Confederacy in which army officers would supervise compliance with Reconstruction policy. On 2 March 1867, Congress overrode Johnson's veto of the first Reconstruction Act and passed an appropriation bill for the army containing a rider that became known as the Command of the Army Act, requiring that all presidential orders pass through the general in chief and prohibiting his removal or relocation. Soon after the Reconstruction Act went into effect, its rigorous enforcement by Major General Philip H. Sheridan in the Fifth Military District (Louisiana and Texas) irritated Johnson, whose hands were tied by the fact that Sheridan was a great favorite of Grant.
In August, Johnson struck at Secretary of War Edwin M. Stanton, who had long been a Radical agent in the presidential camp and was protected by congressional allies through the Tenure of Office Act, which prohibited removal of cabinet officers without the consent of the Senate. Johnson suspended Stanton and appointed Grant acting secretary of war. Johnson knew that he could not succeed in his high-handed removal of Stanton without replacing him with the most popular man in the country; Grant accepted rather than allow the army to fall into unfriendly hands.
Johnson and Grant managed this uneasy partnership until Congress reassembled at the end of 1867, quickly evincing a determination to reinstate Stanton and placing Grant in the untenable position of obeying either his commander in chief or Congress. Grant told Johnson that he intended to resign the office of secretary of war because to hold firm would make him liable to fine and imprisonment under the Tenure of Office Act. Johnson asked Grant to delay his resignation and believed that he had agreed to do so. Through misunderstanding (as Grant's friends believed) or bad faith (as Johnson believed), Grant surrendered the office to Stanton before Johnson had an opportunity to nominate an alternative candidate who might have garnered enough Republican support to achieve confirmation. The restoration of Stanton led to a stormy cabinet confrontation during which Johnson accused Grant of lying. Publication of the exchange of acrimonious correspondence that followed the cabinet meeting completed the process of rupture between president and general.
Johnson's renewed efforts to remove Stanton led to an impeachment trial, with Grant now considered a firm supporter of the removal of Johnson. The break with Johnson provided adequate evidence to Republicans that Grant could be counted in their party. Grant's dislike of Johnson and his policies had increased to the point that he believed that duty demanded his acceptance of a presidential nomination, despite his personal preference for remaining in the army.