I also didn’t know about it. Here is some Wikipedia for anyone interested

Unlike most modern pump-action shotguns, the Winchester Model 1897 (versions of which were type classified as the Model 97 or M97 for short) fired each time the action closed with the trigger depressed (that is, it lacks a trigger disconnector). Coupled with its five-shot capacity, this characteristic allowed troops to fire the whole magazine with great speed by simply keeping the trigger held and running the action as quickly as possible, known as “slam-firing”. This made it extremely effective in close combat, such that troops referred to it as the “trench-sweeper” or “trench broom”. Shortly before the end of the war, the German government protested the use of shotguns in combat, claiming it to cause unnecessary suffering.[23][24] The Model 1897 was used again in World War II by the United States Army and Marine Corps, where it was used alongside the similarly militarized version of the hammerless Model 1912.[25] Some were still in service during the Korean War[26] and the Vietnam War.[27]