Southend claimed promotion to the Coca-Cola Championship and Swindon were relegated to League Two after the penultimate weekend in League One.
A 2-2 draw at Swansea combined with a series of favourable results elsewhere sent the Shrimpers up.
Rory Fallon and Freddy Eastwood both scored two goals apiece as Swansea maintained their grip on the final play-off spot although they must win their last fixture at Chesterfield to be certain.
Swansea had been more threatening in the opening stages with Lee Trundle going close on a couple of occasions before Fallon’s fierce drive put the Swans ahead in the 19th minute.
However, the Shrimpers were level just nine minutes later when Eastwood converted.
Fallon restored the Swans’ advantage after 34 minutes before Eastwood claimed his second when he lifted the ball over the keeper in the 63rd minute.
Colchester all-but guaranteed promotion with a 2-0 victory to plunge struggling Rotherham into even deeper trouble.
The Us opened the scoring after a quarter of an hour when Shaun Barker headed an own goal before Mark Yeates rounded off a slick move to seal victory in the 53rd minute.
Brentford claimed an apparent winner when Kevin O’Connor hit a 20-yard shot into the top corner in the 84th minute but Hartlepool hit back to score a last-minute equaliser through Michael Nelson.
It denied Brentford the opportunity to move into an automatic promotion spot but it gives Pools a lifeline as they look to climb out of the relegation zone of the final day of the season next week against Port Vale.
Huddersfield missed the opportunity to challenge for one of the top-two places after they suffered a shock home defeat by Yeovil.
The Terriers had taken an eighth-minute lead when David Graham broke clear and slotted into the corner.
Phil Jevons drew the visitors level through a penalty before he got his, and Yeovil’s, second with a superb long-range free-kick with 20 minutes to go.
Huddersfield are, however, guaranteed a shot at the play-offs.
Nathan Tyson drew Nottingham Forest level when he slotted home his 23rd goal of the season in the 53rd minute after Bournemouth had taken a shock lead at the City Ground. However, Forest could not find a winner and are still being edged out of the play-offs by Swansea on goal difference.
At the other end of the table, Swindon were relegated following a 1-1 draw with Bristol City, who have a mathematical, but highly unlikely, chance of making the play-offs.
Aaron Brown had put the Robins ahead shortly after half-time but David Cotterill’s equaliser condemned Swindon to the bottom rung of the football league.
The identity of the other relegated clubs is still unclear, however, after Hartlepool’s draw at Brentford.
However, the greatest drama was at the National Hockey Stadium when Milton Keynes Dons and Tranmere scored three goals in the last minute with the visitors emerging victorious, 2-1, to guarantee safety.
The hosts entered the game in fine form, with Rovers on a miserable run, but David Partridge seemed to have given the visitors victory with a headed own goal in the final minute.
Izale McLeod pulled one back before Delroy Facey secured Tranmere’s safety.
The Dons now visit Rotherham, one above the drop zone, with victory the only option.
Elsewhere, Doncaster ended Oldham’s play-off hopes with a 1-0 win; Barnsley and Bradford drew 0-0; relegated Walsall won 1-0 at Gillingham; Port Vale beat Chesterfield 3-1 and Scunthorpe defeated Blackpool 1-0.