Christopher Schindler gave Huddersfield a narrow victory, his header lifting them to a 1-0 over Slavisa Jokanovic's side - leaving them in all sorts of bother.
"It's huge for us," Wagner said to 'Sky Sports'. "We really have now the winning feeling back, and a clean sheet as well, it's for sure one of the most important wins we have had in the last three years, because after 10 games without a win and some unlucky situations, everyone needed the belief back and we have done that today.
"Have you ever not won a game for six and a half months? It's difficult to explain but obviously, the biggest problem for us was that we had so many good performances in the past, especially at home, Liverpool, Tottenham as well, Burnley away, but without goals, points or a win.
"Last weekend [in a 3-0 defeat at Watford] we under-performed and did not look solid defensively, but we were better today and nothing is more important than the winning feeling and the happy faces in the dressing room and around the whole club."