Hans von Gronau

At the outbreak of World War I, Gronau was recalled from retirement to take command of the newly formed IV Reserve Corps as part of the 1st Army, which was on the right wing of the forces that invaded France and Belgium as part of the Schlieffen Plan offensive in August 1914. His main objective was to cover the vulnerable right flank of Von Kluck's 1st Army. On 5 September, when the French 6th Army launched its surprise attack on Ourcq, a tributary of River Marne, they were brought under heavy fire by German guns. As darkness fell, von Gronau knew that he had won the necessary time to save the 1st Army from surprise attack and retreated. Next day on 6 September, when the French attacked again, they found the German positions to be empty[1]

In September 1915, Gronau was appointed to command of XXXXI Reserve Corps (swapping places with Generalleutnant Arnold von Winckler). The Corps was upgraded to form Armee-Gruppe Gronau on 20 September 1915. Gronau remained in concurrent command of the Corps and the Armee-Gruppe. It served with the Army of the Bug throughout its existence. On 18 September 1916 it was raised to the status of an Armee-Abteilung (Army Detachment).[2] It remained on the Eastern Front until dissolved on 27 March 1918.[3]

On 4 October 1916 he was awarded the Pour le Mérite for military bravery. He was awarded the Oakleaves (signifying a second award) on 6 August 1918.[4]

On 23 February 1890 Gronau married Luise Gerischer (20 July 1867 – 25 June 1926). The marriage produced three sons. His oldest son was the flight pioneer Wolfgang von Gronau who crossed the Atlantic Ocean from East to West flying a Dornier Wal D-1422 landing in the Hudson River on 26 August 1930.

• Iron Cross (1870) II class
• Iron Cross (1914) I class
• Pour le Mérite (4 October 1916) and Oak Leaves (6 August 1918)
• Order of the Red Eagle I class with Oak Leaves
• Order of the Crown I class

• Armee-Abteilung or Army Detachment in the sense of "something detached from an Army". It is not under the command of an Army so is in itself a small Army.[5]
• Armee-Gruppe or Army Group in the sense of a group within an Army and under its command, generally formed as a temporary measure for a specific task.
• Heeresgruppe or Army Group in the sense of a number of armies under a single commander.

• Cron, Hermann (2002). Imperial German Army 1914-18: Organisation, Structure, Orders-of-Battle [first published: 1937]. Helion & Co. ISBN 1-874622-70-1.CS1 maint: ref=harv (link)
• Hildebrand, Karl-Friedrich; Zweng, Christian (1999). Die Ritter des Ordens Pour le Mérite des I. Weltkriegs, Band 1: A-G. Biblio Verlag, Osnabrück, Germany. ISBN 3-7648-2505-7.CS1 maint: ref=harv (link)