It was formed on mobilization in August 1914 seemingly from the II Army Inspectorate.

[1] Upon the mobilization Max von Hausen (Saxon War Minister) was given command of the 3rd Army which mainly consisted of Saxons.

Upon the stabilization of the front on the river Aisne, Hausen was relieved of his command and replaced by General Karl von Einem.

Repulsing the French First Battle of Champagne (the Champagne-Marne offensive) from February–March and Second Battle of Champagne (September–November) 1915 respectively, the 3rd Army took part in all three battles of the Aisne and defeated the Fourth Army (General Anthoine) part of Groupe d'armées du Centre (General Philippe Petain) during the Second Battle of the Aisne as part of the Nivelle Offensive from 16 April – 15 May 1917.

After suffering severe casualties in battle with the American Expeditionary Force (General of the Armies John J. Pershing) from 26 September – 11 November in the Meuse-Argonne offensive, the army was forced to retreat northwards shortly before the war ended, when it was part of Heeresgruppe Deutscher Kronprinz.