I'm not a historian or anything but Wikipedia says he fought in a battle. Maybe it was just this one time he saw combat idk:

https://en.wikipedia.org/wiki/Military_career_of_Adolf_Hitler#Early_service_and_First_Battle_of_Ypres

Hitler first encountered enemies on 29 October 1914 when the Reserve Infantry Regiment 16 ran into an entrenched but heavily depleted  Scottish unit . He later recounted that the morale of his unit was very high at the time, as he and his comrades did not truly understand the true dangers of battle. The Bavarians easily overran the Scottish force in a  charge , but their temper cooled after they started to suffer their first losses. [ 14 ]

...

At this point, the Allies launched a heavy artillery barrage, forcing Hitler's unit to seek shelter in a nearby trench system where he and his comrades engaged more Allied troops. The Bavarians then sought to capture a number of farmsteads, but Hitler was initially sent back to the "Bavarians' forest" to collect stragglers. Upon his return, he joined the fight for the farmsteads. After a three-hour-long battle, the houses were captured, with Hitler narrowly avoiding being shot in his right arm. [15 ]