A sixth successive win for Chatham saw them beat Cray Valley to win the Isthmian South East title with a game to spare on Saturday.
They led at half-time thanks to a Jack Evans penalty before Matt Bodkin struck after the restart and, despite Denzel Gayle pulling one back for the Millers late on, Kevin Hake’s troops held on as they earned promotion in their first campaign back at the level in style.
There was much at stake for both sides so a nervy start at the Bauvill Stadium ensued. But away players Thomas Chambers and returning captain Gayle caused early problems on the left-hand side.
Ike Orji and Che Krabbendam linked-up well on Chatham’s right in the 13th minute, only for optimistic penalty protests for a foul on player-assistant manager Danny Kedwell to be dismissed.
Bodkin crossed from the left midway through the first period but Evans and striker Kedwell were unable to convert, the latter's back-post shot being deflected wide.
Cray Valley had a string of opportunities shortly after the half-hour mark which saw Ade Adeyemo drag a shot inches wide before Hassan Ibrahiym - on his 100th club appearance - had a deflected shot that also missed the target.
But Chats broke the deadlock against the run of play in the 35th minute in front of another big crowd of 2,329.
Ashley Nzala beat Valley keeper Chris Lewington to a long ball and went to ground, with referee Mark Gidman pointing to the spot and cautioning Lewington. And Evans blasted into the roof of the net his 22nd goal this season in emphatic style.
Just five minutes later, however, play-off chasing Cray went close to a leveller. Defender Kiki Oshilaja dragged wide from a good area inside the box and they could consider themselves unlucky to trail at the interval.
Chatham’s Nzala had a massive chance two minutes after the restart, which he sent narrowly over the crossbar.
Home keeper Ben Bridle-Card was equal to Daniel Bennett’s low free-kick just before the hour while veteran Chats man Kedwell hobbled off and was replaced by Emmanuel Oloyede.
A second Chats substitution on 64 minutes then saw Callum Peck come on for Nzala before Evans had appeals for a second spot-kick waved away.
Soon after, 30-year-old Evans, once again, felt he had won a second penalty after he had sent a corner - half-cleared - back in with interest. But the referee had blown his whistle as a visiting defender had taken the fierce effort straight to the face.
Chats did go two goals to the good with 10 minutes left, though. An in-swinging cross from Bodkin went right the way across the area and into the far corner, with Lewington left stranded, to spark joyous scenes.
The away team had always been in the contest, however, and Gayle pulled one back after a right-wing cross in the 86th minute.
But Chatham held on throughout the nervy final few minutes and will play in Isthmian Premier next season.
Chats, who play National League South Welling in their Kent Senior Cup Semi-Final on Tuesday, will end the league campaign at Littlehampton next weekend, having already earned a second successive promotion.
Tommy Osborne’s men will finish their season with home fixtures against VCD and Sheppey, and they could yet still earn a play-off berth despite dropping to seventh after the 2-1 loss.
The hosts named an unchanged starting line-up, although they did make a change on the bench, where Dean Beckwith came in for fellow experienced defender Richard Orlu.
There were two changes for the Millers as Gayle returned in place of the injured Adam Coombes and Mitchell Nelson replaced Alex Bentley.
Chatham Town: Bridle-Card, Orji, Cooper, Robins, Butler, Evans, Kedwell (Oloyede 59mins), Drury, Bodkin, Nzala (Peck 64mins), Krabbendam. Subs not used: Lock, Taylor, Beckwith.
Cray Valley: Lewington, Nelson, Chambers, Oshilaja, Tumkaya, Black, Gayle, Samuels, Bennett, Ibrahiym (Anau 79mins), Adeyemo. Subs not used: Silvera, Majekodunmi, Medhurst.
Referee: Mark Gidman.