Ten-man Town claimed a point from the archetypal 'game of two halves' at The County Ground courtesy of goals from Charlie Austin and a late equaliser from Michael Rose.
Danny Wilson's side started a disjointed half slowly, and had an early scare as Scott McGleish thought he had headed Orient in front after three minutes, but the veteran striker was ruled offside.
The visitors shaded what was a tame opening 20 minutes of the match, after which Town began to find their feet, but still struggled to break down a stubborn visiting rearguard.
David Ball and Paul Caddis saw half chances go begging on 22 and 28 minutes respectively, but it remained a largely drab affair with little goalmouth action.
As the match passed the half hour mark, Town began to look increasingly threatening, and might have gone in front on 31 minutes, and Jon-Paul McGovern saw a first time volley deflected narrowly over the bar.
Clear cut opportunities were still at a premium, and both goalkeepers remained untested as the half drifted towards its conclusion - Dean Cox's long-range effort the closest either side would come before the whistle.
After a similarly uneventful opening to the second half, referee Trevor Kettle, who had threatened to seriously affect the game throughout, did just that after 53 minutes, when he thrust a red card at Alan Sheehan after the Irishman had shown his studs in a challenge with Matt Spring.
Mr Kettle did not even need to be surrounded by players in the textbook modern day fashion to brandish the card, as he did just that within seconds of the challenge.
Danny Wilson made the inevitable alteration, with Michael Rose replacing David Ball, and seconds later had David Lucas to thank for keeping the scores level, as the 'keeper parried a long range Dean Cox effort just out of the reach of the onrushing Jimmy Smith.
O's midfielder Matt Spring went one better minutes later, as he picked up the ball 25 yards from goal, cut inside and curled it into the far corner past Lucas.
However, just as it looked like Town fans might have to settle for a long afternoon, their side hit straight back, as substitute Rose picked out Charlie Austin with an inch-perfect cross, and the returning striker glanced the ball into the far corner to notch the equaliser for the hosts.
Orient might have restored their lead soon after, but Lucas was again on hand to deny Dean Cox; pushing the impressive midfielder's cross-cum-shot over the bar.
After Town's initial rally, the visitors were beginning to benefit from their numerical superiority, and found themselves back in front on 76 minutes, as former Town striker Alex Revell nipped in at the near post to nod home a Charlie Daniels cross and come back to haunt his former side once again.
The goal looked to have taken the stuffing out of Danny Wilson's side, but substitute Rose had other ideas, as, after Matt Ritchie had been fouled on the edge of the box, the left-back stepped up and drilled a stunning effort into the top corner to level the scores for a second time.
For a moment it looked as Town might go on to win it, but in fact it was the visitors who mounted a late onslaught, centring mostly around the ever dangerous Cox.
However, despite a late Jimmy Smith volley that trickled just wide, Town held on for what they will consider a well earned point after hugely testing encounter.