He grew up in his home town, attended the Lyceum there and, from March 1831, the Ludwigsburg Officers Training Institute [de].

When Generalleutnant Moriz von Miller [de] took over the War Office on 2 July 1850; he made Hardegg his adjutant.

[3] Knowing the danger the lack of centralization the Southern German States, in October 1866, Hardegg sent a memorandum to Baden, Württemberg, Hesse-Darmstadt, and Bavaria to work on standardizing the equipment, organization, and training of their armies.

In addition to his professional and specialist knowledge, Hardegg cultivated music with a special passion, both as a pianist and as a composer.

The daughter married the Bavarian Colonel Freiherr von Freyberg-Eisenberg in Dillingen, Hardegg's son became a captain and commander of the 8th Württemberg Infantry Regiment No.