WASHINGTON—Celebrating and commemorating the myriad contributions of previously overlooked heroes, the Smithsonian American History Museum unveiled a new exhibit Thursday honoring the thousands of U.S. pets who devoted their time and talents to the war effort while their owners fought overseas in World War II. “Before the war, pets were largely relegated to the home, performing such small tasks as catching mice or fetching slippers. That changed after Pearl Harbor,” said researcher Bethany Karl, explaining that at the war’s outset, manufacturers of munitions turned to pets to fill jobs at factories and shipyards vacated by men leaving to enlist. “This exhibit contains hundreds of hours of previously unscreened film documenting cats riveting together fighter planes at the Willow Run Aircraft Factory 31, dogs pulling M4 Sherman frames down the line at the Lima Tank Works, and parrots delivering vital communications at the labyrinthian Charlestown Army Ammunition Plant. During the war, these animals proved capable of anything their owners could do, transforming forever their place in American society.” Karl noted that budgetary issues had forced Smithsonian officials to cancel a small addendum to the exhibit focusing on the brutal 1946 beating of hundreds of dogs, cats, and other companion animals during their ill-fated postwar attempt to unionize.