Answer
The title "Lion of Lechistan" originated from the heroic and decisive victory achieved by Sobieski at the Battle of Vienna. In 1683, he commanded a multinational force that valiantly repelled the Ottoman attackers, liberating Vienna from a two-month siege and dealing a significant blow to the Ottoman Empire's expansionist ambitions. This iconic triumph bolstered Sobieski's reputation as a courageous military leader and elevated his standing in European history.