Funny and historical. I've never even heard of Oswald.
I think he was realated to Steamboat Itchy.
Not surprising, since he was a silent cartoon. Walt's real achievement wasn't creating Mickey, it was figuring out how to do sync sound on a cartoon (for which most credit should go not to Walt but to his Kansas City chum Ub Iwerks).
And not only was Mintz stealing Oswald, he had also secretly poached a large number of Walt's animators, including Harman and Ising (who would eventually end up at MGM and give Hanna and Barbera their starts). Meanwhile, at Universal, Oswald would eventually end up in the hands of their resident genius, Walter Lantz. Oswald's last appearance was a cameo in 1952, although his regular series had ended in 1938. Lantz would eventually create Woody Woodpecker.
The whole story of how Charles Mintz basically stole Oswald is a key moment in Disney history, not only forcing Walt to create Mickey, but also setting him on the course of becoming his own studio so that he wouldn't be in such a position again.