James Norwood gave the Blues an early lead but Keenan Appiah-Forson levelled for West Ham’s U21s to leave the scoreline 1-1 at half-time at Portman Road in Town’s first Papa John’s Trophy tie of the season.
Town boss Paul Cook made 10 changes from the weekend 5-2 loss to Bolton on Saturday with Sam Morsy skippering on his debut and young centre-half Albie Armin handed his senior bow.
Tomas Holy was in goal with Kane Vincent-Young - the only player to have started against the Trotters but who lasted only 21 minutes before being subbed - at right-back and Matt Penney on the left.
Luke Woolfenden and Armin were the centre-halves with Morsy and Tom Carroll - making his first Town start - in the middle of midfield.
Idris El Mizouni made his second start of the season in the number 10 role with Louis Barry on the left and Kayden Jackson the right with Norwood the lone out-and-out striker.
Jon Nolan was among the subs for the first time this season, while youngsters Cameron Humphreys, Zanda Siziba and Elkan Baggott were also on the bench.
After both teams taking the knee had been warmly applauded, the game got under way in steady drizzle.
And Town went in front in only the second minute via the first attack of the game. After good work from El Mizouni on the left, Penney drove towards the area and fed Vincent-Young breaking on the right.
The former Colchester man cut inside to Carroll, who looped into the area. Norwood appeared to get a flick on it causing West Ham keeper Kristian Hegyi to mishandle and the Blues striker stabbed in his first goal of the season.
Town continued their bright start and on seven Vincent-Young crossed for Norwood from the right but the Blues’ number 10 was already through his shot when the ball arrived and it bounced off him for a goalkick.
West Ham threatened for the first time in ninth minute when Daniel Chesters was sent away down the right behind Penney but Woolfenden did well to get across to cut out his low ball into the area.
That attack proved to be a sign of things to come and in the 12th minute the visitors levelled. The ball was neatly worked in from the left with Town failing to put in a serious challenge and Appiah-Forson shot across Tomas Holy and into the net. The Czech keeper got his right hand on it and will feel he probably should have kept it out.
In the 22nd minute Hammers skipper Ajibola Alese was booked for felling Norwood after the goalscorer had successfully chased a long Jackson ball down the right.
The visitors almost created a second in the 24th minute when Armstrong Okoflex sent a dangerous ball across the six-yard area which the shaky Holy allowed beyond him but with no Hammers player there to add the final touch.
The Blues, whose performance had drifted after their bright start, began to show more of a threat and on 28 Jackson crossed low from the right but Norwood was unable to turn towards goal at the near post and it was cleared ahead of Barry behind him.
A minute later, Jackson shot first against Norwood and then over the bar from some distance out.
Just after the half-hour, Kamarai Swyer was played in on the left of the box and hit a shot which Holy was forced to palm behind.
On 35, Norwood took down a long ball forward from Woolfenden and fed Jackson breaking on the right. The former Accrington man sent it low across the six-yard area but too far in front of Norwood and Barry. Five minutes later, Norwood flicked a Carroll free-kick from the left wide, Penney having been fouled.
As half-time approached, the Blues were well in control, passing the ball around confidently with Carroll and Morsy at the centre of things, although without creating another chance.
During two minutes of injury time El Mizouni was booked for a foul on Harrison Ashby, the Tunisia international’s second transgression of the night.
Town had got off to the ideal start via Norwood’s early goal and might well have scored again in the opening minutes, however, once again they quickly allowed the opposition to get back into it, although from a West Ham perspective it was a well worked goal.
Both sides had one or two opportunities to go in front after that - Norwood had looked dangerous throughout - with the Blues finishing the half in a controlled manner with experienced midfield pair Carroll and Morsy increasing in influence.
Town: Holy, Vincent-Young, Woolfenden, Armin, Penney, Morsy (c), Carroll, Jackson, El Mizouni, Barry, Norwood. Subs: Hladky, Baggott, Humphreys, Nolan, Siziba, Chaplin, Pigott.
West Ham U21: Hegyi, Okoflex, Alese (c), Ekwah, Ashby, Chesters, Laing, Longelo, Swyer, Appiah-Forson, Baptiste. Subs: Kinnear, Dju, Rosa, Diallo, Perkins, Forbes, Casey. Referee: Charles Breakspear (Surrey). Att: 4,231 (West Ham: 150).