Two things come to mind, Chase. One, McClellan was so invested in training and equipping his troops, he did not want to risk them in battle without great superiority in numbers. Two, he believed Allen Pinkerton's vastly overblown estimates of Confederate troop strength. Even when in possession of Lee's Gen. Order 191 for Antietam, he could not bring himself to attack when he had Lee at a huge disadvantage. Istead, he waited ubtil Lee was able to concentrate his men. Stan