You can also click the Add layer mask icon at the bottom of the Layers panel (which, by default, selects Reveal All). Note that if you already have a layer mask on the layer, this icon will change to Add vector mask. Or you can click the Add a Layer Mask icon in the Properties panel.
The top American ace of all time, the U.S. Ace of Aces was Richard Ira Bong. He shot down 40 Japanese planes in the Pacific. Over the years, there's been a lot of ink spilled about the relative scores of German and American aces. 27 Americans shot down over 20 enemy planes.
In March of 1953, Major George Jones became the 30th American ace of the Korean war. By this time peace talks were starting, and when Ed Heller was shot down on the wrong side of the Yalu it created quite a furor. Heller, along with Fischer, Mahurin. and Bettinger became a POW; three other Korean aces (Risner, Low, & Kasler) later became POWs in Vietnam.