Ipswich manager Paul Lambert said he and his team were left feeling "gut-wrenched" and "horrible" following the 1-1 draw with Birmingham which confirmed their relegation to Sky Bet League One.
Their long run in the Championship came to an end with four games left to play to bring to an end 17 consecutive seasons in the second tier.
Goals came just after the start of both halves with Lukas Jutkiewicz putting the visitors ahead in the seventh minute only for Gwion Edwards to reply in the 46th.
But Birmingham manager Garry Monk said his team was not ruthless enough, especially in the first half when they should have gone in at the break further ahead and failed to take the three points.
Lambert said: "It was a game of two halves. Birmingham were better than us in the first half and we were better than them in the second half.
"But you're going to get that with young players at times. They are kids that have come through from academy football and right into the first team.
"They are going to learn on the job that's the only way they are going to learn.
"The majority have been thrown in and that's why I think there's a lot of good things to look forward to here but and all credit to them in the second half, we were excellent.
"The supporters have been unreal and I feel gutted for them, it's phenomenal and it's overwhelming, you see it at the end of the game, it's incredible the support."
He said of the fact this side had now been relegated: "It's gut-wrenching, it's horrible, it's like a blow. But we have great things to forward to."
Dropping to the third tier – a level the club have not played at since 1957 – has long looked a matter of inevitability though for a team who have has won just four games all season.
Birmingham took the lead when full-back Maxime Colin skipped past tackles from Myles Kenlock and Teddy Bishop to cross for Jutkiewicz to calmly slot home with his left foot from inside the six-yard box.
But Ipswich drew level when substitute Kayden Jackson's perfect left-wing cross found Edwards who fired home.
Monk said the overriding fact of the game was that they should have been further ahead before the break.
He said: "We created enough chances to be in a really comfortable position and any level, especially in this league, if you don't take your chances you leave yourself open to that fightback.
"I said it in the build-up to this game one thing Ipswich are doing is they are fighting and we left ourselves open to that fight in the second half with the scoreline still only being 1-0 by not being clinical enough.
"That's the difference today, we weren't clinical enough.
"Even with that fightback which Ipswich gave in the second half we still created three really, really good chances which we should have taken.
"We didn't and that was a big difference for us from taking three points and ending up with one.
"We would have liked to take the three points today but we were not ruthless enough."
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