Minibikes (Welbikes) hit the beach at Normandy June 6,1944
While there is a lot of evidence that the Welbike was used during training and battle excercises, as far as I have been able to tell, the Welbike was used in only two major battles, D-Day on June 6, 1944 and Operation Market Garden, September 17, 1944.
Below is the only photographic evidence I've seen of the Welbike in action. This is the Headquarters company of the 4th Special Service Brigade, making their way from LCI(S)s (Landing Craft Infantry Small) onto 'Nan Red' Beach, JUNO Area, at St Aubin-sur-Mer at about 9 am on June 6, 1944. Look carefully at the center of the photo and you'll see two commandos carrying a Welbike between them. Look even more carefully at the top of the ramp leading down from that ship and you'll see another Welbike who's owner is getting ready to carry it down the rather steep ramp! There may be a third Welbike at the base of the ramp, just being picked up by two men.