General-in-chief military forces in the field, as the generals-in-chief did in the 19th century. The rank of "General of the Armies of the United States" was conferred upon General John J. Pershing in 1919 and to Lieutenant General George Washington (posthumously) in 1975 by acts of Congress. Washington's date of rank was retroactively dated to 1799, so that he will always be the senior ranking general of the United States Army. (American general ranks and titles may be a little confusing; however, as reference is cited the public domain information of the Center for Military History of the United States Army
Major general a variety of staff positions. The professional head of the Royal Marines currently holds the rank of major-general. From 1 April 1918 to 31 July 1919, the Royal Air Force maintained the rank of major-general. It was superseded by the rank of air vice-marshal on the following day. Major-general is equivalent to rear admiral in the Royal Navy and air vice-marshal in the Royal Air Force. In the United States Army, a major general (MG) typically commands a division of 10,000–20,000 soldiers and is capable of fully independent field operations. They may also serve as deputy commanders in 3-star commands