Original: Having completely beaten the main Ottoman army under Grand Vizier Koca Yusuf Pasha in the Battle of Rymnik , he captured the greater part of Wallachia , including Bucharest , being welcomed by the population after the flight of Prince Nicholas Mavrogenes ( see History of Bucharest ) , and soon after becoming a Field Marshal .
Simplified: Having completely beaten the main Ottoman army under Grand Vizier Koca Yusuf Pasha in the Battle of Rymnik , he captured the greater part of Wallachia , including Bucharest , being welcomed by the population after the flight of Prince Nicholas Mavrogenes .