Defense Secretary Pete Hegseth has ordered hundreds of the U.S. military’s generals and admirals to gather on short notice — and without a stated reason — at a Marine Corps base in Virginia next week, sowing confusion and alarm after the Trump administration’s firing of numerous senior leaders this year. The highly unusual directive was sent to virtually all of the military’s top commanders worldwide, according to more than a dozen people familiar with the matter. It was issued earlier this week, against the backdrop of a potential government shutdown, and as Hegseth’s overtly political moves have deepened a sense...