Staff of Essex's Army
September 1642
- Captain General: Robert Devereaux, 2nd Earl of Essex1)
- Sgt-Major-General: Sir John Merrick
- Provost Marshal General: Captain James Seigneur
- Carriage Master General: Captain Thomas Richardson
- Officers of the Lord General's Train:
- Treasurer at Wars: Sir Gilbert Gerrard
- Muster-Master General: Lionel Copley Esq.
- Advocate of the Army: Dr Isaac Dorislaus
- Secretary to the Army: Henry Parker Esq.
- Auditor of the Army: Robert Chambers
- The Council of War:
- President: Sir John Merrick, Sgt-Major-General
- Sir William Balfour, Lt General of Horse
- Colonel James Wardlaw
- Colonel Thomas Grantham
- Colonel Sir William Constable
- Philibert Emmanuel de Boys, Lt General of Artillery
- Dr Isaac Dorislaus, Advocate of the Army
- Officers General of Horse:
- Lord General: William Russel, 5th Earl of Bedford
- Lt General: Sir William Balfour
- Quartermaster General: John Dalbier
- Commissary for the Horse: Sir Edward Dodsworth
- Provost Marshal General: John Baldwine
September 1643
At the First Battle of Newbury2)
- Commander-in-Chief: Robert Devereux, Earl of Essex
- Lieutenant-General of the Horse: Sir William Balfour (absent) duties probably performed by Sir James Ramsay
- Major-General of Foot: Philip Skippon
- Muster-Master-General: Captain Lionel Copley
- Commissary-General: Colonel Hans Behre
- Adjutant-General of the Foot: Lieutenant Colonel Bayley
- Lieutenant-General of the Ordnance: Sir John Merrick