James Norwood gave Town a sixth-minute lead but Jonson Clarke-Harris netted a 38th minute equaliser to leave the Blues’ game at Peterborough 1-1 at half-time.
Skipper Chambers came in at right-back for Luke Matheson, who dropped to the bench, while Ward was back on the left with Myles Kenlock among the subs.
Bishop returned at the top of a narrow midfield diamond with Norwood joining Troy Parrott up front, Town eschewing their usual 4-3-3/4-2-3-1 system presumably due to the tricky London Road pitch.
Former Posh wideman Gwion Edwards and Freddie Sears were also on the bench, while Luke Thomas was missing from the 18.
Peterborough were without star attacker Siriki Dembele with Mo Eisa coming into an otherwise unchanged side.
Despite being cold, there was little sign of snow in the Peterborough area but with the pitch muddy and short on grass.
After both teams and the officials took a knee in support of Black Lives Matter, Joe Ward hit a powerful fifth-minute shot which Tomas Holy claimed confidently.
A minute later, the Blues, wearing their burgundy and blue third strip, went in front. Holy kicked long - in line with the Blues’ early approach on the Sunday morning pitch - and Frankie Kent and Posh skipper Mark Beevers had got in one another’s way as they tried to head clear on the edge of the box.
Bishop reacted quickly and deftly played a pass to the left of the box for Norwood, who hit a low shot which beat keeper Christy Pym at his near post.
On 14 Downes, playing in the holding role with Dozzell ahead of him to his left and Judge to the right, was booked for what looked a solid ball-winning challenge on Dan Butler on halfway with the Posh players appealing that it should have been a red card. While the Blues midfielder won the ball, some referees may well have deemed it an out-of-control tackle.
There was a scare for Town in the 22nd minute when a ball in from the right deflected over Holy. However, the keeper moved quickly to get himself in the way as Eisa shot at goal from eight yards.
In the 28th minute, with Peterborough trying to play football despite the surface and the Blues more direct and looking to counter, Eisa cut in from the left and hit a shot into Holy’s arms.
Just before the half hour, Holy missed his punch from a corner but somehow managed to bundle it behind for another flag-kick before it dropped for a Posh player.
Norwood needed treatment for a knock on 32 soon after fouling Ward in the centre circle as Town looked to break following a Posh corner having left three players up spread widely along the halfway line at the flag-kick, as they had against Blackpool at the weekend.
Eisa shot over from the edge of the area in the 36th minute and three minutes Posh levelled.
Butler crossed from the left with Judge unable to cut it out with Chambers chasing back from being involved further up the field, and Jonson Clarke-Harris rose between Ward and Mark McGuinness to nod back across Holy and into the corner of the net, the striker’s 17th goal in all competitions this season.
In injury time Downes was spoken to by referee Ben Toner for speaking out of turn after a decision had gone against Dozzell having been booked for his earlier challenge.
Soon afterwards, Toner’s whistle ended a half which had started perfectly for the Blues with Norwood’s well-taken goal.
However, Town had failed to threaten after that with Peterborough able to pass the ball around despite the pitch and use the wide areas left open by the Blues’ narrow system.
The Peterborough goal was well-deserved when it came, although looked one the Blues will see as having been preventable.
Peterborough: Pym, Butler, Thompson, Beevers (c), Kent, Eisa, Taylor, Clarke-Harris, Brown, Szmodics, Ward. Subs: Gyollai, Burrows, Jones, Blake-Tracy, Kanu, Hamilton, Mason.
Town: Holy, Chambers (c), Woolfenden, McGuinness, Ward, Dozzell, Downes, Bishop, Judge, Parrott, Norwood. Subs: Cornell, Kenlock, Matheson, Harrop, Edwards, Sears, Drinan. Referee: Ben Toner (Lancashire).