I've always admired Ulysses Grant but when you read about his own personal struggles, he truly is a compelling person. Graduated near the bottom of his class at West Point, spent his lieutenant years posted in California away from his wife (whom he was madly in love with and fell into deep depression being separated from her, hence his heavy drinking), then served in Mexico under Zachary Taylor and resigned shortly thereafter to try his hand at farming in Missouri. He was a terrible farmer, worse shopkeeper, could keep his books straight or turn a profit in business, ended up being indebted to his father-in-law and living in his house with his wife in kids and working for him on the farm. That was, until the war started, and every man who had been a regular officer had their commision reinstated. They say the rest is history, but it isn't, he had a helluva time in the early years of the war, huge bouts of depression, stuck in non-combatant positions, until he was able to take command of a regiment, then a brigade, division, and soon Lincoln had placed him in charge of the Union army, because he was the only commander that knew how to fight an army. "You find the enemy, fight him, and do not let him go until he can fight no more."