How did George McClellan earn the nickname Tardy George?

George McClellan earned the nickname "Tardy George" due to his cautious and often overly deliberate approach to military strategy during the American Civil War. His reluctance to engage in decisive battles and frequent delays in launching attacks frustrated both his superiors and his troops. This hesitancy was particularly evident during the Peninsula Campaign in 1862, where he failed to take advantage of opportunities to defeat Confederate forces, leading to criticism of his leadership.