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. This conflict between the two brothers led to a correspondence, which was published in 1769. 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. In reality, he died from a brain tumor.