The 1st Army during World War I, fought on the Western Front and took part in the Schlieffen Plan offensive against France and Belgium in August 1914.

Commanded by General Alexander von Kluck, the 1st Army's job was to command the extreme right of the German forces in attacking the left flank of the French Army and encircling Paris, bringing a rapid conclusion to the war.

His army had the greatest striking power of the offensive, a density of about 18,000 men per mile of front (about 10 per metre).

The First Army captured Brussels on 20 August and was almost successful in defeating France but was halted just 13 miles outside the French capital in the First Battle of the Marne that took place in early September.

[3] 2nd Army bore the brunt of the Allied attack in the Battle of the Somme.