How did Lincoln know to stick with Grant before the completion of the Vicksburg campaign?

Grant was one of the few Union generals who would fight without being "pushed," and without needing reinforcements to enable him to outnumber the Confederates. Early in the war, he won notable victories at Fort Henry, and Fort Donelson. At the latter post, he started an attack with only equal ground forces, with his only advantage the heavier guns of the Union gunboats.

At Shiloh, he beat back an attack by an initially larger Confederate force under Albert Sidney Johnston (who was killed in the battle), the one active general that outranked Robert E. Lee, and that some historians consider better than Lee. After that, he pursued the Confederates into Mississippi.

In the early days of the Vicksburg campaign, Grant had more troops than its defender, John C. Pemberton, but was actually outnumbered by a combination of Pemberton's force and a relieving force under General Joseph E. Johnston. To defeat these forces separately, Grant severed his lines of communications with the Mississippi River, and had his troops live of the land for a two-week campaign inland. (The more senior Johnston ordered Pemberton to leave Vicksburg and "chase" Grant so that the two Confederate armies would have a chance to join, but Pemberton disobeyed.Unlike the other Union generals, Grant was bold to a fault.

Question:
Lincoln was sticking by Grant, whom he'd never met, well before his big victories at Vicksburg(May 18, 1863 – Jul 4, 186) and Chattanooga(Nov 23 to Nov 25, 1863). How did Lincoln know to do that? What made him so confident in Grant?

Answer:

Grant was being politically savaged in 62 and 63; because his reputation and notoriety were rising, eclipsing the Union Commanders in the East. It's true that Vicksburg was one of Grants signature victories in the West, but before that great victory Grant had already established himself as a Major General and top Union Commander.

• February 6, 1862
  Grant had won the battle of Fort Henry, which was the first notable victory of the civil war for the Union.

• February 16, 1862
  Ulyseses S. Grant won the battle of Fort Donelson earning him the nickname "Unconditional Surrender" Grant as well as his promotion to Major General

• April 6-7, 1862 Battle of Shiloh. Grant hpad invaded deep into the south. Grant is surprised by superior numbers on the first day fighting, but is able to overcome his initial losses and pull out a union victory in what was the bloodiest battle of the Civil War up to that point.

Before the battle of Shilo Grant was actually relieved of his field command of the invasion of Tennessee was turned over to one of his subordinate. This was so ordered by General Halleck who at the time was Grants superior.

Battle of Shiloh
In early March, Union Maj. Gen. Henry W. Halleck, then commander of the Department of the Missouri, ordered Grant to remain at Fort Henry, and on March 4 turned field command of the expedition over to a subordinate, Brig. Gen. C. F. Smith, who had recently been nominated as a major general.[18] (Various writers assert that Halleck took this step because of professional and personal animosity toward Grant; however, Halleck shortly restored Grant to full command, perhaps influenced by an inquiry from President Abraham Lincoln.)

• September 19, 1862 Battle of Iuka, Grant defeats Confederate General Sterling Price in Iuka Mississippi

• October 3–4, 1862 Battle of Corinth

What was happening back east? McClellan's Peninsula Campaign July 1862 had every advantage over the Confederates. McClellan's amphibious landing of 120,000 men outnumbered Joseph Johnston army defending Richmond by 2-1. McClellan sent another sizable force of nearly 50,000 men overland from Northern Virginia to engulf Richmond in a pincer maneuver. McClellan's Union Army had advanced all the way to the outskirts of Richmond before Lee drove them all the way back to Washington with his army of no more than 60,000 men. Lee conducted the Seven Day's battles where his numerically inferior force fought eight major battles in seven days to drive McClellan from Richmond.

Still worse for the Union, Stonewall Jackson taken 17,000 men, and engaged the three Union Armies McClellan had sent overland to reinforce his siege at Richmond in the Shenandoah Valley Campaign. The Union forces confronting Jackson consisting of 52,000 men. Jackson defeated them in a series of battles which drew forces and resolve away from McClellan and ultimately had Jackson threatening Washington DC causing panic in the Capital City.

All told the Peninsular Campaign demonstrated a stark contrast with the conduct of the War in the East with regard to that in the West under U.S. Grant. It lead to Lee's first invasion of the North, and ultimately to Lincoln dismissal of McClellan as the Armies top commander after the Battle of Antietam Sept 17, 1862. and thus the attacks on Grant as one of the Union's most successful commanders as his rivals for command sought to tarnish Grant's reputation with a campaign of fear uncertainty and doubt to postpone Lincoln from jumping him into command of all union forces. Something Lincoln eventually did.

Sources:

• Fort Henry
• Fort Donelson
• Battle of Shiloh
• Battle of Iuka
• Battle of Corinth
• Peninsula Campaign
• Seven Day's battles
• Shenandoah Valley Campaign
• Battle of Antietam

From Comments:
I'm not sure that holds water. Grant might have been in overall command for corinth, but Rosecrans was on the ground and seems to have gotten credit for that. Grant was commanding an army at Iuka, but i haven't read that it moved the needle for him. Did it? Also, by that logic, Halleck was in command of Grant, so why didn't his stock rise further? Or maybe it couldn't. Regardless, Grant was on the the ground, running the major campaigns from vickburg on, so the characterization of him being in overall command for the Overland Campaign doesn't really fit all his work before vickburg. – dwstein

Grant was in overall command. Grant was also on the ground and planned both Corinth and Luka. At Luka the column of troops Grant was with did not participate in the battle. Perhaps that is what you are thinking of. Some strange auditory effect occurred and they didn't realize the battle was occurring initially. But Grant was there and had directed Rosencrans's actions.

General William Rosencrans
(Rosencrans) received command of the entire army (Union Army of Mississippi) on June 26, and in July (of 1863), added the responsibility of commanding the District of Corinth. In these roles, he was the subordinate of Maj. Gen. Ulysses S. Grant, who commanded the District of Western Tennessee and the Army of the Tennessee, from whom he (Rosencrans) received direction in the Iuka-Corinth campaign in September and October 1862.

@dwstein, Divisions could be commanded by a Major General but typically by a lower ranking Brigadier Generals, Corps were commanded Major Generals, Armies by Major Generals. And some Major Generals like Grant in 1863 commanded multiple armies. Generally the guy in overall charge in the field as Grant was, who planned and directed Rosencrans, both at Luka and Corinth, typically is credited. As Meade was at Gettysburg, as McClellan was at Antietam. That doesn't detract or compete with credit given to the army commanders like Rosencrans.

In the Tennessee Campaign, Grant commanded all the troops in Western Tennessee consisting of the Union Armies of Tennessee, Mississippi, and Ohio.

Preface

@JMS - I don't offer this answer as a substitute, but in addition to yours.

@dwstein - The source for information cited and provided below comes from:

• John Y. Simon, Lincoln and Grant (Lincoln Fellowship of Wisconsin, 1984);
• Brooks D. Simpson, Ulysses S. Grant: Triumph Over Adversity, 1822-1865 (Boston: Houghton Mifflin, 2000);
• Jean Edward Smith, Grant (Simon & Schuster, 2000)

as found summarized on Abraham Lincoln's Classroom.org in the featured article Abraham Lincoln and Ulysses S. Grant. At the bottom of the article there are 138 References cited.

Answer

It appears Lincoln's confidence in Grant was solidified with Grant's victory at Vicksburg. Prior to Vicksburg:

General Grant was a source of admiration and source of concern at the White House. Of particular concern was Grant’s reputed fondness for liquor. He began to drink seriously when posted by the army in California. Biographer William S. McFeely wrote

“Without friends, without Julia and the two boys, without any responsibilities on the base, he was at the danger point….Grant did not leave the army because he was a drunk. He drank and left the army because he was profoundly depressed.”

Concern about Grant’s drinking surfaced in late 1861. In Galena, Grant had met his future aide, John A. Rawlins. Rawlins was only person besides Grant’s wife who could protect him from demon whiskey. Historian Kenneth P. Williams wrote:

“On December 30 Rawlins found time to write a very long and important letter. It was an answer to one of the 21st from Congressman Washburne, who was much disturbed by reports that Grant was intemperate. Rawlins said that he had found Grant ‘a strict abstinence man’ when he himself reached Cairo, and he had been told by men who knew Grant well that such had been his habit for the past five or six years.”

Historian James McPherson noted that

“Grant probably drank less than his peers, but he could not hold his liquor well.”

In Late 1861 Grant's drinking was becoming well known in Washington. Rather than relying on rumors, Lincoln and Secretary of War Edwin M. Stanton sent several military and civilian visitors to investigate personally and report their findings back to Washington. Upon their arrival at his headquarters, Grant became aware that his status was cause for concern in Washington. The article goes on to explain:

Among these [visitors] were former New York Tribune editor Charles Dana, Congressman Elihu Washburne, and Adjutant General Lorenzo Thomas – as well as a team of doctors. Rather than taking offence at these visits, Grant received the visitors cordially – realizing that in so doing he could control the substance and tone of their reports. Brooks Simpson wrote: “The positive reports of Dana, Thomas, and the medical officer reassure Lincoln about Grant’s ability.” Lincoln however worried about Grant’s strategy – until he started repulsing and containing the Confederates. Simpson wrote:

“Lincoln believed the campaign ‘one of the most brilliant in the world.’ The six weeks of siege that followed, coming at a time when Robert E. Lee’s army was moving northward into Maryland and Pennsylvania, caused Lincoln some concern, but in the main he was relieved. ‘I rather like the man,’ he told one visitor. ‘I think I’ll try him a little longer.’” [emphasis added]

Shortly thereafter, during the Tennessee campaign:

General Ulysses S. Grant came to the attention of President Lincoln and the nation when in February 1862 Grant captured two Confederate garrisons on the Tennessee River, Fort Henry and Fort Donelson. “U. S.” Grant got the nickname “Unconditional Surrender” Grant after he demanded unconditional surrender from the Confederate commander of Fort Donelson.

While undoubtedly this raised Grant's political capital in Washington, Lincoln still had reservations. But Grant managed to avoid any serious blunders that could have ended his career. The article explains Grant's status with Lincoln prior to Vicksburg like this:

For the first two years of the war, President Lincoln and General Grant had to size each other up from a distance. Historian William B. Hesseltine contended:

“With his work as a military administrator adding nothing to his reputation, Grant’s rise to success was hampered by many difficulties. Contrary to later legend, Lincoln was slow to [perceive] Grant’s fighting qualities.” [emphasis added]

Historian John Y. Simon states:

“While Grant fought the war in the West, his only contact with Lincoln came through correspondence, and there was no great amount of it. Yet the man in the White House kept a careful eye on Grant, who held a series of posts so vital that mismanagement would have been fatal.”

It was Grant's success at Vicksburg that solidified Lincoln's faith in his military abilities, but there were still political questions that remained. According to the article:

What marked Grant for promotion by the President was the surrender and capture on July 4, 1863, of Vicksburg, Mississippi, the last remaining Confederate citadel on the Mississippi River. [emphasis added] If one way didn’t work, Grant tried another to attack the city. President Lincoln had been doubtful about Grant’s strategy, but grateful that it worked. The chief executive followed Grant’s progress on the maps he kept in his office. On July 13, President Lincoln wrote Grant:

“I do not remember that you and I ever met personally. I write this now as a grateful acknowledgement for the almost inestimable service you have done the country. I wish to say a word further. When you first reached the vicinity of Vicksburg, I thought you should do, what you finally did–march the troops across the neck, run the batteries with the transports, and thus go below; and I never had any faith, except a general hope that you knew better than I, that the Yazoo Pass expedition, and the like, could succeed. When you did get below, and took Port-Gibson, Grand Gulf, and vicinity, I thought you should go down the river and join Gen. [Nathaniel] Banks; and when you turned Northward East of the Big Black, I feared it was a mistake. I know wish to make the personal acknowledgement that you were right, and I was wrong.”

As historian James M. McPherson tersely observed: “Grant was…Lincoln’s man the rest of the war.” [emphasis added]

When Grant aide and army chaplain John Eaton visited the White House in 1863,

“Mr. Lincoln immediately began to ask me questions about his ‘fighting General,’ as he already called Grant, passing from him to the consideration of other men whom he trusted, – to the personal characters of various subordinate officers, and what they did and said. The searching inquiries never for a moment became trivial; the motive behind each was too formidable for that. During the whole of my acquaintance with the President, he seemed to me to be doing all in his power to measure the personal character of prominent men. He gauged the strength of his armies by their leaders. He seemed constantly to be taking these measurements, and when he had taken them, to lay them aside in that wonderful brain of his for future use.”

Historian E. B. Long wrote “that all through 1863 Grant shows up more and more as a great organizer of war, a side of his genius too often submerged because of the more spectacular events he engineered.” Long argued that “Lincoln recognized this ability when he ordered Grant east to take command of all the armies and to direct the total war strategy. Lincoln needed a general who could fight, but, even more, one who could coordinate.”

Lincoln wanted a military commander who could direct the entire Union military effort – but not be tempted like Generals George B. McClellan and John C. Fremont – into trying to direct the nation from the White House. Grant scholar John Y. Simon wrote of Lincoln:

“Before appointing Grant lieutenant general, he wanted assurance that the new rank would not be used as a springboard to the White House. Two close friends of Grant from Galena were interviewed and gave full assurance that Grant’s interests were purely military. Only then did Lincoln proceed with the appointment.” [emphasis added]

This article, and the books used and cited as references therein, appear to provide documentary evidence that Lincoln was not sold on Grant until Vicksburg, but prior to that he did exhibit faith in him by not succumbing to rumors about Grant, but rather investigating the matter for himself through trusted emissaries, and watching Grant's progress for signs of military and personal failure or success.

Sources

The 138 sources referenced in the above cited article are too numerous to list here, but can all be found at the bottom of the article's page at AbrahamLincolnsClassroom.org.