Both sides had several chances - as well as a disallowed goal each in the first half - but neither could convert in the 90 minutes, leaving Ennis to take centre-stage with a fine set-piece effort that earned the young Reds three points. United's record now reads five wins and four defeats from the opening nine fixtures.
Travis Binnion's side are next in action on Tuesday night, facing Rochdale at Spotland in our third National League Cup match. The young Reds have won the previous two, 3-2 at Forest Green Rovers and 4-0 at Altrincham.
Starting with a three-man defence supplemented by wing-backs Harry Amass and Jaydan Kamason, United contained West Ham well for the most part in an even first half.