There is no rank of Marshal
General
Field Marshal is the highest military rank in Pakistan Army.
The Royal Air Force rank of Air Marshal is equivalent to Vice-Admiral (Royal Navy) and Lieutenant-General (British Army and Royal Marines).
Rommel earned the rank of Field Marshal in the Battle of Gazala.
An Air Vice-Marshal is a rank in the Royal Air Force, between air commodore and air marshal, equivalent to an army major general.
Marshal (Marechal)
Normally, Air-Chief-Marshal Exceptionally, Marshal of the Royal Australian Air Force¹
An Air Chief Marshal is someone who belongs to the most senior rank active in the Royal Air Force.
If you meant the highest rank, the Military is divided into three divisions, each with their own highest rank:Navies Admiral of the Fleet Armies Field Marshal Air forces Marshal of the Air Force
The marshal is the highest ranking piece. However, they can be beaten by bomb. (And the spy to if the spy attacks the marshal.)
In most structured armies it is the rank of 'Field Marshal'.