The Dublin-native has now presided over the Reds’ longest championship run with next weekend’s last-eight showdown against either Donegal or Armagh to be Louth’s eighth contest of the summer.
Captain Sam Mulroy struck the decisive score in the one-point victory over Cork on Sunday, exactly six years on from arguably the county’s worst-ever defeat, a 10-point loss away to Leitrim in an All-Ireland qualifier.
“It was euphoric when the final whistle went,” said Brennan.
“I’m so proud and delighted for the group of players, the clubs, county board and all the mentors who put work into these lads over the last number of years.
“As a new manager coming in, you’re getting the lads in the here and now but a lot of the donkey work was put in by clubs, development squads and the local schools. It’s a credit to all those people.
“The euphoria that we saw on the pitch at the end, with the crowd running in, that’s something I was, thankfully, able to experience as a player but this Louth group that we have now, they’re just incredible and deserve all the accolades that come.
“They’re a fabulous team. We’re like a group of rowers – everyone is just pulling in the same direction and doing the very best we can. The group are such a very easy bunch to manage. They’re high achievers, they’re very coachable and they have great ideas themselves.
“We just amalgamate everything together but it sometimes comes down to a bit of heart, desire and resilience – you saw all that today. It’s an incredible achievement.”
Back in March, Louth stood on the verge of relegation from Division 2 after losing four of the opening five matches. Since then, only Kerry and Dublin have beaten the Reds over nine outings.
“Getting a win under your belt just helps to galvanise and make worthwhile the work that was going on in the background.” the manager added.
“When these lads have been asked to win knockout games, Fermanagh in the league was a knockout game and Kildare ended up being a knockout game in the league, and these boys answered.
“There was a 49-year wait for a victory over Meath and the lads answered that as well. Now they’ve broken new ground by beating Cork for the first time in the championship since ’57. It’s just an incredible group and when it matters, the lads are able to stand up.”
Meanwhile, Cork boss John Cleary, who was hoping to lead the Rebels to a third successive last eight appearance, was coy when asked about his future.
“We’ll see now,” he said. “I’m three years at it and anyone involved in a county team will tell you it’s tough going, it’s a full-time job.
“I’ll make no decision one way or the other. It’s definitely not a definite because the amount of effort that goes into it from all and I just have to see how the lads that worked with me this year are fixed.
“And even my own circumstances, it is tough going and we’ll just mull on it now for a few days and see after that then.”
On the defeat, he added: “We should have won that game but we didn’t win the game. In fairness, Louth hung in there at times. We were in a good position at half-time and then they clawed their way back into it.
“We got several chances and then a sucker punch of a goal that they gave them something to cling onto. We got back from that and got a chance there at the end and didn’t close it out and it’s unbelievably disappointing at this stage.”
