Was that the only battle that he excelled in?
http://en.wikipedia.org/wiki/George_Armstrong_Custer
On May 24, 1862, during the pursuit of Confederate General Joseph E. Johnston up the Peninsula, when Gen. Barnard and his staff were reconnoitering a potential crossing point on the Chickahominy River, they stopped and Custer overheard his commander mutter to himself, "I wish I knew how deep it is." Custer dashed forward on his horse out to the middle of the river and turned to the astonished officers of the staff and shouted triumphantly, "That's how deep it is, Mr General!" Custer then was allowed to lead an attack with four companies of the 4th Michigan Infantry across the Chickahominy River above New Bridge. The attack was successful, resulting in the capture of 50 Confederates seizing the first Confederate battle flag of the war...
In his first command, Custer affected a showy, personalized uniform style that alienated his men, but he won them over with his readiness to lead attacks (a contrast to the many officers who would hang back, hoping to avoid being hit); his men began to adopt elements of his uniform, especially the red neckerchief. Custer distinguished himself by fearless, aggressive actions in some of the numerous cavalry engagements that started off the campaign, including Brandy Station and Aldie...
Custer's style of battle was often claimed to be reckless or foolhardy, but military planning was always the basis of every Custer "dash". As Marguerite Merrington explains in The Custer Story in Letters, "George Custer meticulously scouted every battlefield, gauged the enemies weak points and strengths, ascertained the best line of attack and only after he was satisfied was the 'Custer Dash' with a Michigan yell focused with complete surprise on the enemy in routing them every time."
It's notable that Custer failed to the the last at Little Big Horn, likely because of his contempt of the Indians as a fighting force. It was clearly a fatal mistake.