When his brother Frederick became king in 1740, Augustus became heir presumptive and moved into Fredrick's former residence, the Crown Prince's Palace in Berlin.

When his older sister Louisa Ulrika married the King of Sweden in 1744, she founded the Ordre de l'Harmonie, of which Augustus was one of the first recipients.

Augustus served his brother as a general in the War of the Austrian Succession and distinguished himself in the Battle of Hohenfriedberg.

But in the Seven Years' War, owing to the fatal retreat of Zittau during the Battle of Kolin in 1757, he incurred the wrath of his brother the King, and withdrew from the army.

[1] Augustus died suddenly in 1758 at Oranienburg, according to some of "a broken heart", in reference to his brother Frederick II's harsh treatment of him for his incompetent military leadership in the Battle of Kolin.