Born in Luxembourg to a noble family of partial Huguenot extraction, François was exposed to a military life from an early age.

[1] After attending cadet schools in Wahlstatt and in Berlin, François entered the Prussian Army on 15 April 1875 as a Seconde-Lieutenant (2nd Lieutenant) in the 1st Regiment of Foot Guards (1.

[2] On 23 April 1889, François was posted as a general staff officer to the XV Corps based in Strasbourg (Imperial Territory of Alsace–Lorraine).

[4] His task was to defend the easternmost regions of East Prussia against a Russian attack directed at the key city of Königsberg.

The 8th Army would be expected to hold out against significantly larger Russian forces until it could be reinforced by troops coming from the west after the expected quick defeat of France, in accordance with the Schlieffen Plan, which would guide German forces in the opening phase of a war in which Germany faced both France and Russia.

On 17 August the overall German theater commander, General Maximilian von Prittwitz und Gaffron, nervously eying the advance of the Russian left wing far to the south, ordered François to retreat while under heavy attack from Rennenkampf.

He counterattacked Rennenkampf's massive army, bringing on the Battle of Stalluponen, and won a surprising victory while inflicting 5,000 casualties and taking 3,000 prisoners.

Although not trusted by the new German commanders Paul von Hindenburg and Erich Ludendorff due to his previous disobedience, François played the decisive role in the upcoming Battle of Tannenberg.

On 27 August, François attacked the lead elements of Samsonov's army and began to make steady advances into their rear.

[5] When Hindenburg and Ludendorff went south to lead the 9th Army in Russian Poland, François remained with his corps in East Prussia and led it with much success in the First Battle of the Masurian Lakes the following month.

The telegram impressed the Kaiser so much that he immediately relieved Schubert and, on 3 October, gave François temporary command of the 8th Army.

[5] After some time spent "on the shelf", François received the command of the XXXXI Reserve Corps[a] on 20 December 1914,[4] and after a spell in the West, he returned to the Eastern Front in April 1915 where he took part in the Spring Offensive that conquered Russian Poland.

[4][1][5] After the war ended, François returned home and wrote several books on military history, including the best-seller (in Germany) Marneschlacht und Tannenberg in 1920.