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.
A flying ace or fighter ace is a military aviator credited with shooting down several enemy aircraft during aerial combat. The actual number of aerial victories required to officially qualify as an ace has varied, but is usually considered to be five or more.