In 1863, the outstanding German historian Jakub Caro, in the second volume of his History of Poland, introduced the scientific view that Władysław Opolczyk was the godfather of Władysław Jagiełło. The author came to this conclusion due to the similarity of the name Władysław, which Jagiełło received at baptism in Kraków, with the name of the Prince of Opole, who at that time, and temporarily, as the course of events shows, became closer to Jagiełło. This view was then taken over by other historians writing about the Polish-Lithuanian union, the history of Władysław Jagiełło, Jadwiga, or discussing the mentioned events in their works. After analyzing historical facts and dates, the acceptance of the statement that Opolczyk was baptized by Władysław Jagiełło on February 15, 1386 in Kraków is no more probable than the opposite statement, considering that there is no evidence (apart from Jakub Caro's guess) that that the Duke of Opole was Jagiełło's godfather.