April 26, 1959, and the O's eventually won 3-2 on the strength of a Hoyt Wilhelm five-hitter.
As long as we're talking about '59 Topps, I would humbly suggest that you follow one of the newest card blogs on the scene. Fellow Orioles fan Bob (a.k.a. Commish), who has commented frequently here, has nearly completed the 1959 Topps set and is blogging about each and every card. He offers some of his own memories about the players, highlights of their careers, and his opinions about the cards. It's a quick entertaining read, so check out '59 Topps: One F/G Card at a Time. Oh, and have a good long weekend!