Ever since their first appearance in the 1939 release of The Wizard of Oz, Dorothy's ruby slippers quickly became one of the most iconic pieces of pop culture. But, did you know that other notable events also took place in 1939? In the same year that Dorothy walked down the Yellow Brick Road while wearing the ruby slippers, Germany invaded Poland, Batman first appeared in comics, Lou Gehrig retired from the New York Yankees, and much more. Explore this collection of images to witness key moments from 1939.