Steve Bruce has revealed that he left his position as manager at Hull City "for the sake of the club".
The 55-year-old resigned on Friday, just three weeks before the start of the Premier League season.
After guiding the Tigers back to the top flight by winning the Championship playoff final in May, Bruce admitted that he would consider his future, but last month confirmed his intention to stay.
Almost four weeks later, though, Bruce, who was a reported candidate for the England job before Sam Allardyce's appointment, stepped down.
In an open letter to the supporters, which was published by the Hull Daily Mail, Bruce said: "I have thoroughly enjoyed the last four years and you have played a big part in that. It is rare for a manager to have the backing I've had from fans. It's been unwavering.
"I was made welcome from the minute I walked in through the door and even during the times we struggled, I felt the majority of supporters understood how difficult it was for a club the size of Hull City to reach, and then stay in, the Premier League.
"My biggest regret is having to walk away but it was a decision I had to make for the sake of the club. The last 12 months have been very tough and it felt like the right step for the club to move forward in a different direction and with someone else in charge. I desperately wanted to make it work this summer and be a Premier League manager again but, sadly, it wasn't to be."
Bruce guided Hull to two promotions and an FA Cup final during his four-year spell in charge.
