He was born in Vienna to Wilhelm Graf Daun, also a Field Marshal. Wirich served in the War of Spanish Succession under Eugene of Savoy, and gained his glory in the successful defence of Turin in 1706. He also laid siege to and conquered Gaeta on 30 September 1707. After the war, in 1713 he became first Austrian Viceroy of Naples. In 1718 he lost the Battle of Milazzo during the War of the Quadruple Alliance, when Spain invaded neighbouring Sicily. From 1725 until 1736 he was Governor of Milan.