The history of 18th century diplomacy includes the nameless Colonel Stankiewicz, an envoy of Hetman Branicki to Turkey in 1763-1765. Ensuing research enabled the author to identify the envoy to Istanbul as Marcin Stankiewicz, born in the county of Orsza, in 1743-1746, a cadet at Lunéville and the companion of Kazimierz Krasinski, and then the companion of Józef Ossolinski on his tour across Europe. The dates of the military promotions granted to Stankiewicz were discovered and his links with certain families in the Commonwealth were reconstructed. It is worth stressing the dramatic plight of the emissary who set off to Turkey upon the initiative of Hetman Jan Klemens Branicki in order to seek support against the Czartoryski 'Family' and Russia, and then tried to oppose the candidature of Stanislaw Poniatowski to the throne as well as to support Branicki at a time when Poniatowski had been already elected king. Stankiewicz did not possess sufficient means or support to win influence at the Turkish court; at the same time, he was well aware of the enormous hope attached to his mission by the adherents of the Saxon-republican orientation. Vehemently contested by the Russian representative in Stambul and the supporters of Russia at home, he was perceived even by his political opponents as a true knight errant battling for the sake of a lost cause.