For the whole of that year, it was Henry Halleck.
Ulysses S. Grant.
General Rosencrans was successful in preparing his Army of the Cumberland in 1863. He then began his offensive against Confederate General Braxton Bragg in June of 1863.
Chancellorsville, Virginia.
The Confederate victory at the 1863 Battle of Chancellorsville resulted in the raid into the Union by General Lee. It also resulted in the replacement of Union General Joseph Hooker by President Lincoln in favor of General George Meade to lead the Army of the Potomac and pursue Lee into Pennsylvania.
General in Chief Scott resigned on November 1, 1861. Major General George B. McClellan was then promoted by President Lincoln to succeed Scott as general-in-chief.
In March of 1863, Union General William Sherman informed the governor of Ohio of his views on the war. Sherman informed the governor that "The South is more formidable than it was two years earlier".
Joe Hooker was the commander of the Union first corps (I Corps) at the battle of Antietam. He would later be elevated to commander of the Union Army of the Potomac. He served in that capacity from January 1863 through June 1863. He would command this army at the Battle of Chancellorsville, a Union defeat, and was removed from command just prior to the Battle of Gettysburg.
If it is the Battle of Gettysburd you refer to, the Union General George Meade and Confederate General Robert E. Lee fought.
Ulysses S. Grant
On June 23, 1863, President Lincoln, Secretary of War Stanton General in Chief Henry Halleck and Major General Joseph Hooker met at the War Department. Their purpose was to design a plan in response to General Lee's incursion into Union territory. The meeting produced no tangible results and only added to the confusion of the Union leadership.
On October 12, 1863, a Rebel Major General Richard S. Ewell defeated a Union cavalry force at Jeffrsonton, Virginia. Ewell then advanced on the same day to Fauquier White Sulphur Springs, scoring another minor victory.
In 1863, General in Chief Henry Halleck had appointed Major General John Scofield as the commanding officer of the Department of Missouri. Scofield was a New Yorker and a graduate of West Point. Missouri was an important border state and a slave state. It was vital that Missouri and other border states remained in the Union.