Order of Battle

German army:

8th Army

CC Generaloberst Paul von Beneckendorff und von Hindenburg
(before 22.8 Generaloberst von Prittwitz und Gaffron),
COS major general Erich Ludendorff
(before 22.8 major general Graf von Waldersee),
1. Generalstabsoffizier (ACOS G3) lieutenant colonel Max Hoffmann,
Oberquartiermeister (ACOS G4) major general Grünert,
General of the Engineers major general Kasten.

Ist Army Corps

General of the Infantry Hermann von Francois.
COS Colonel Freiherr von Schmidtseck
1. Generalstabsoffizier (ACOS G3) major von Massov

1st Infantry Division (lieutenant general von Conta, COS major von Graberg)

1st Infantry Brigade (major general von Trotha) 1st Grenadier Regiment (lieutenant colonel Eggerss)
41st Infantry Regiment (colonel Schönfeld) 2nd Infantry Brigade (major general Paschen) 3rd Grenadier Regiment (colonel von Wedel)
43rd Infantry Regiment (colonel von Eisenhart-Rothe) 8th Uhlan Regiment (lieutenant colonel Freiherr Schäffer von Bernstein)
1st Field Artillery Brigade (major general Moewes) 16th Field Artillery Regiment (colonel Bromeis)
52nd Field Artillery Regiment (colonel Hellwig)

2nd Infantry Division (lieutenant general von Falk, COS major Goedel)

3rd Infantry Brigade (major general Mengelbier) 4th Grenadier Regiment (colonel Stern)
44th Infantry Regiment (colonel von Loeper) 4th Infantry Brigade (major general Boëß) 33rd Fusileer Regiment (lieutenant colonel Weicke)
45th Infantry Regiment (colonel Maaß) 10th Horse-Grenadier Regiment(lieutenant colonel Berring)
2nd Field Artillery Brigade (major general Fouquet) 1st Field Artillery Regiment (colonel von Sydow)
37th Field Artillery Regiment (lieutenant colonel von der Lippe)

1st Heavy Field Artillery Battalion (from 1st Regiment)(major Christ)
1st Engeneer Battalion (major Queisner)
14th Aviation Battalion (captain Heinrich)

XVIIth Army Corps

General of the Cavalry von Mackensen.
COS lieutenant Colonel von Dunker)
1. Generalstabsoffizier (ACOS G3) major Gount von Schwerin

35th Infantry Division (lieutenant general Hennig, COS major Engelien)

70th Infantry Brigade (major general Schmidt von Knobelsdorf) 21st Infantry Regiment (colonel Brunnemann)
61st Infantry Regiment (major Lüdecke) 87th Infantry Brigade (major general von Hahn) 141st Infantry Regiment (lieutenant colonel von Steinkeller)
176th Infantry Regiment (major Runge) 4th Horse-Grenadier Regiment (lieutenant colonel Freiherr von Loën)
35th Field Artillery Brigade (major general Uhden) 71st Field Artillery Regiment (lieutenant colonel Hecht)
81st Field Artillery Regiment (lieutenant colonel Bertog)

36th Infantry Division (lieutenant general von Heineccius, COS major von Winning)

69th Infantry Brigade (major general von Engelbrechten) 129th Infantry Regiment (colonel Breßler)
175th Infantry Regiment (colonel Schleenstein) 71st Infantry Brigade (Colonel von Dewitz) 5th Grenadier Regiment (colonel Freiherr von Eichendorff)
128th Infantry Regiment (colonel von Tresckow) 5th Hussar Regiment (colonel Freiherr von Barnekow)
36th Field Artillery Brigade (major general Hahndorf) 36th Field Artillery Regiment (major Waldener)
72nd Field Artillery Regiment (lieutenant colonel von Rabenau)

1st Heavy Field Artillery Battalion (from 17th Regiment)(major Mahrenholz)
17st Engeneer Battalion (major Härms)
17th Aviation Battalion (captain Dincklage)

XX Army Corps

General of the Artillery von Scholtz
COS Colonel Hell
1. Generalstabsoffizier (ACOS G3) major Kunhardt von Schmidt

37th Infantry Division (lieutenant general von Staabs COS major von Gazen gen Gaza)

73rd Infantry Brigade (major general Wilhelmi) 147th Infantry Regiment (colonel Nitzsch)
151st Infantry Regiment (colonel Dorsch) 75th Infantry Brigade (major general von Böckmann) 146th Infantry Regiment (colonel von Hendebreck)
150th Infantry Regiment (colonel Küster) 11th Dragoon Regiment (colonel Maatz)
37th Field Artillery Brigade (colonel Giebeler) 73rd Artillery Regiment (colonel Forst)
82nd Artillery Regiment (lieutenant colonel Plantier)

41st Infantry Division (major general Sontag, COS major Weniger)

72nd Infantry Brigade (major general Schaer) 18th Infantry Regiment (colonel Mecke)
59th Infantry Regiment (colonel Sonntag) 74th Infantry Brigade (major general Reiser) 148th Infantry Regiment (colonel von der Osten)
152nd Infantry Regiment (colonel Geisler) 10th Dragoon Regiment (lieutenant colonel von Lewinski)
41st Field Artillery Brigade (major general Neugebauer) 35th Artillery Regiment (lieutenant colonel Wilke)
79th Artillery Regiment (lieutenant colonel Marcus)

2nd Heavy Field Artillery Battalion (of 5th Regiment)(major Bissinger
26st Engeneer Battalion (major Koch)
15th Aviation Battalion (captain Donat)

Ist Reserve Corps

lieutenant general Otto von Below.
COS Colonel Count von Posadowsky-Wehner
1. Generalstabsoffizier (ACOS G3) major Keller

1st Reserve Division (lieutenant general von Förster, COS captain Heinersdorf)

1st Reserve Brigade (major general Barre) 1st Reserve Regiment (lieutenant colonel von Sommerfeld und Falkenhayn)
3rd Reserve Regiment (lieutenant colonel von Steuber) 72nd Reserve Brigade (major general Licht) 18th Reserve Regiment (lieutenant colonel Freiherr von Lützow)
59th Reserve Regiment (lieutenant colonel Modrow) 1st Uhlan Reserve Regiment (major Berner)
1st Reserve Artillery Regiment (lieutenant colonel Schultz)

36th Reserve Division (major general Kruge)

69th Reserve Brigade (major general von Homeyer) 21st Reserve Regiment (lieutenant colonel Heyn)
61st Reserve Regiment (colonel Immanuel) 70th Reserve Brigade (major general Bett) 54th Infantry Regiment (colonel von Tippelskirch)
5th Reserve Regiment (lieutenant colonel Count zu Reventlow) 1st Hussar Reserve Regiment (major von Borcke)
36th Reserve Artillery Regiment (lieutenant colonel Lannert)

3rd Reserve Division (lieutenant General von Morgen, COS major Frantz)

5th Reserve Brigade (General Major Hesse) 2nd Reserve Regiment (lieutenant colonel Rodig)
9th Reserve Regiment (lieutenant colonel Wobring) 6th Reserve Brigade (General Major Krause) 34th Infantry Regiment (colonel Hein)
49th Reserve Regiment (lieutenant colonel Freiherr von Eberstein) 5th Dragoon Reserve Regiment (major von Götz)
3rd Reserve Artillery Regiment (major Ehrhardt)

Landwehr Division Unger (General Major von Unger, COS captain Liebmann) 20th Landwehr Brigade (from the fortress of Thorn, see below)
Brigade Semmern (from the fortress Graudenz, see below)
70th Landwehr Brigade (see below) Landwehr Division Goltz (lieutenant General Freiherr von der Goltz, COS captain Söldner - first units arriving on August 27th)

33rd Landwehr Brigade (General Major von Oertzen) 75th Landwehr Infantry Regiment (lieutenant colonel Stwolinski)
76th Landwehr Infantry Regiment (lieutenant colonel Billig) 34th Landwehr Brigade (lieutenant General von Pressentin) 31st Landwehr Infantry Regiment (lieutenant colonel von Lillienhof-Zwowitzki)
84th Landwehr Infantry Regiment (colonel Becker) Landwehr Cavalry Regiment (captain von Sydow)
Three batteries (landwehr and reserve)

2nd Landwehr Brigade (Colonel Freiherr von Lupin, in the fortress of Königsberg) 4th Landwehr Infantry Regiment
33rd Landwehr Infantry Regiment
2nd Landwehr Cavalry Squadron (from Ist Army Corps)
2 landwehr batteries (from Ist Army Corps) 6th Landwehr Brigade (General Major Krahmer, COS captain Giehrl) 34th Landwehr Infantry Regiment (lieutenant colonel Freiherr von Dalwigk zu Lichtenfels)
49th Landwehr Infantry Regiment (lieutenant colonel Kipping)
Three Landwehr Cavalry Squadrons (from IInd Army Corps)
Two Landsturm Batteries (from IInd Army Corps) 70th Landwehr Brigade (General Major Breithaupt) 5th Landwehr Infantry Regiment (lieutenant colonel Zimmer)
18th Landwehr Infantry Regiment (lieutenant colonel von Wedel)
Four Landwehr Cavalry Squadrons (from XVIIth and XXth Army Corps)
Two Landsturm Batteries (from XVIIth Army Corps)

1st Cavalry Division (lieutenant General Brecht, COS captain Freiherr von Gienanth)

1st Cavalry Brigade (major general von Slasenapp) 3rd Curassier Regiment (lieutenant colonel von Lewinski)
1st Dragoon Regiment (lieutenant colonel Count von Kanitz) 2nd Cavalry Brigade (major general Freiherr von Kap-herr) 12th Uhlan Regiment (colonel von Below)
9th Horse-Grenadier Regiment (lieutenant colonel von Koppelow) 41st Cavalry Brigade (major general von Hofmann) 5th Curassier Regiment (lieutenant colonel von Rex)
4th Uhlan Regiment (major Charisius)

From the fortress Thorn:

35th Reserve Division (lieutenant General von Schmettau, COS captain Mertens)

5th Landwehr Brigade (lieutenant General von Mühlmann) 2nd Landwehr Infantry Regiment (colonel von Reuter)
9th Landwehr Infantry Regiment (lieutenant colonel Schmidt) 20th Landwehr Brigade (lieutenant General von Hertzberg) 19th Landwehr Infantry Regiment (lieutenant colonel Freiherr von Lüttwitz)
107th Landwehr Infantry Regiment (lieutenant colonel Senft von Pilsack) 4th Reserve Machine gun Battalion
3rd Heavy Reserve Horse Regiment
Eight batteries (reserve and replacement)

From the fortresses Kulm, Graudenz and Marienburg:

Brigade Semmern (General Major von Semmern) 6 infantry battalions, 1 squadron and 4 batteries (all replacement units)

Fortress Königsberg

Main Reserve (lieutenant General Brodrück)

Replacement Brigade (Colonel Weicke) 1st Replacement Regiment
2nd Replacement Regiment 9th Landwehr Brigade (lieutenant General Clausius) 24th Landwehr Infantry Regiment
48th Landwehr Infantry Regiment 1st Reserve Dragoon Regiment
Replacement Cavalry Regiment (from I army Corps)
six batteries (reserve and replacement)

Other forces: 16½ infantry battalions, 3½ squadron and 57 batteries (reserve, landwehr, landsturm and replacement units)

Fortress Boyen (Colonel Busse) 4½ infantry battalions, 1 squadron and 8 batteries (landwehr, landsturm and replacement units)

Russian army:

Northwest Front

CC General of the cavalry Shilinski
COS lieutenant general Oranowski

Ist Army

CC General of the cavalry von Rennenkampf
COS lieutenant general Mileant

IInd Army Corps (general Scheidemann) 26th Infantry Division
43rd Infantry Division IIIrd Army Corps (general Jepantschin) 25th Infantry Division
27th Infantry Division IVth Army Corps (general Aliew) 30th Infantry Division
40th Infantry Division XXth Army Corps (general Smirnow) 28th Infantry Division
29th Infantry Division 5th Grenadier Brigade
1st, 2nd Guard Cav.-Div, 1st, 2nd, 3rd Cav.-Div, and 1st cavalry brigade.
53rd, 54th, 56th, 57th, 72nd and 73rd Reserve Division

IInd Army

CC General of the cavalry Samsonow
COS major general Postowski
ACOS G2 colonel Lebedew
ACOS G3 colonel Wjalow
ACOS G4 general Filimonow

Ist Army Corps (general Artamanow, dismissed by Samsonow on August 28th,
new commander general Duschkewitsch) 22nd Infantry Division
24th Infantry Division VIth Army Corps (general Blagowjeschtschenski) 4th Infantry Division
16th Infantry Division XIIIth Army Corps (lieutenant general Klujew) 1th Infantry Division
36th Infantry Division XVth Army Corps (general Martos, COS general Matschugowski) 6th Infantry Division
8th Infantry Division XXIIIrd Army Corps (general Kondratowitsch) 3rd Guard Division (general Sirelius)
2nd Infantry Division 4th, 6th and 15th Cavalry Division