In Così fan tutte, Mozart and his librettist Lorenzo Da Ponte have the two male protagonists, Ferrando and Guglielmo, return in disguise to test, by wager, the fidelity of their fiancées. The choice of the disguise as Albanians, at first sight exotic and comic, resonates deeply with late 18th-century memories of the 1683 Siege of Vienna, in which the Albanians served…