Grant first got Lincoln's attention with his Paducah Proclamation.
Even then a very jealous Halleck tried to cashier him.
Yes, and without Lincoln's favor, Grant probably would have quit after Shiloh. Lincoln's quote about Grant was, "I can't spare this man, he fights."
Grant finished in the middle of his West Point class, and was a Quarter Master during his first stint in the army. When the Civil War broke out he was a clerk in father's store, and was turned down for multiple commissions. When he finally got one he was given a very difficult group of men to command.
He dodged a bullet...literally...at Shiloh.
He came within inches of having his head blown off a couple of times at Belmont.
Anyway. I'm a big fan of Grant since reading his memoirs some years ago which I recommend. While being very talented in many areas, he had close to zero ambition. He went from being a nobody to the most famous man in the world within the span of a few years.
Personal memoirs usually bore the bejeebers out of people. Grant's captures the reader like a fine novel.