What were the reasons previously given?
Sky Sports News had suggested that the former executive vice-chairman had planned to leave his role at the end of the year anyway and his sudden departure last night was not as a result of the Super League.
However, The Star has revealed that Woodward - who has endured a lot of criticism during his time at Old Trafford - felt he had no choice but to resign after underestimating how fierce the opposition would be to the proposals.
Indeed, he's thought to have realised he had made one of the biggest mistakes of his professional career.
After being surprised by the reaction, he reportedly phoned Joel Glazer to inform him of his decision to leave.
What has Gary Neville said about Woodward?
Sky Sports pundit and Old Trafford legend Gary Neville has been publically fighting the idea of the Super League and last night described Woodward as the "trunk of the tree".
"Every single executive who goes and sits at the Premier League table, every single executive who sits on these UEFA and FIFA committees, they need throwing out of that club," he said.
"There's no way that they can turn up at an audience and be trusted.
"So Ed Woodward knew his time in football was finished. Probably this morning and he's probably done that to probably keep away from the criticism that would be coming his way in the next few months.
"However, Ed Woodward is the trunk of the tree. We now need to go for the roots."
Just how involved was he?
After his departure, The Athletic revealed that Woodward had his 'fingertips all over' the Super League plan.
The Daily Mail also claimed that he was forced to hold an emergency meeting with some Manchester United players who were far from impressed with the plans. Not long after that, journalist Mike Keegan suggested captain Harry Maguire stepped in to confront him.
What have United players said about the Super League?
Former United star Ander Herrera was also one of the first major European players to condemn it.News Now - Sport News