On February 6, 1915, the precursor of the division
Truppenabteilung Westernhagen consisted of: • '
Troop Detachment (Truppenabteilung
) Westernhagen' • I., II. & Ersatz Battalions/ Landwehr Infantry Regiment 8 • Ersatz Regiment Keller (2 Btl) • Fortress MG Detachment 5 Thorn • 2nd & 7th
Landsturm Squadrons, V A.K. • 2nd Ersatz Battery/ Field Artillery Regiment 56 • Landsturm Battery, XVIII A.K. • 1 captured Russian battery • 4th Battery/ Reserve Foot Artillery Regiment 11 (Heavy Field Howitzers) • 2nd battery/ Reserve Foot Artillery Regiment 15 (10-cm Cannons) • 2nd Reserve Co./ Pioneer Battalion 17 The 89th Infantry Division was formed as an understrength division, with only two infantry regiments. It later received a third regiment, becoming a regular
triangular division. The order of battle of the division on August 9, 1915, was as follows: • 178. Infanterie-Brigade • Landwehr-Infanterie-Regiment Nr. 8 • Infanterie-Regiment Nr. 375 • 2. Landsturm-Eskadron/V. Armeekorps • 7. Landsturm-Eskadron/V. Armeekorps • Feldartillerie-Abteilung Nr. 89 • 4.Kompanie/Reserve-Fußartillerie-Regiment Nr. 5 • 4.Kompanie/Reserve-Fußartillerie-Regiment Nr. 11 • 2.Kompanie/Reserve-Fußartillerie-Regiment Nr. 15 • 2.Reserve-Kompanie/Pionier-Bataillon Nr. 17 ==Late-war order of battle==