text: For his edification Lincoln relied upon a book by his chief of staff General Henry Halleck entitled Elements of Military Art and Science; Halleck was a disciple of the European strategist Antoine-Henri Jomini.Lincoln began to appreciate the critical need to control strategic points, such as the Mississippi River.Lincoln saw the importance of Vicksburg and understood the necessity of defeating the enemy's army, rather than merely capturing territory.In directing the Union's war strategy, Lincoln valued the advice of Gen.Winfield Scott, even after his retirement as Commanding General of the United States Army.On June 23–24, 1862, President Lincoln made an unannounced visit to West Point, where he spent five hours consulting with Scott regarding the handling of the Civil War and the staffing of the War Department.General McClellan After the Union rout at Bull Run and Winfield Scott's retirement, Lincoln appointed Major General George B.McClellan general-in-chief.McClellan then took months to plan his Virginia Peninsula Campaign.McClellan's slow progress frustrated Lincoln, as did his position that no troops were needed to defend Washington.McClellan, in turn, blamed the failure of the campaign on Lincoln's reservation of troops for the capital.In 1862, Lincoln removed McClellan for the general's continued inaction.He elevated Henry Halleck in July and appointed John Pope as head of the new Army of Virginia.Pope satisfied Lincoln's desire to advance on Richmond from the north, thus protecting Washington from counterattack.But Pope was then soundly defeated at the Second Battle of Bull Run in the summer of 1862, forcing the Army of the Potomac back to defend Washington.Despite his dissatisfaction with McClellan's failure to reinforce Pope, Lincoln restored him to command of all forces around Washington.Two days after McClellan's return to command, General Robert E.