I guess it all started with Brian Clough & Don Revie (both ferociously competitive Boro lads) back in the early 70’s.
Cloughie’s DCFC side pipped Don Revie’s dirty Leeds team to the Division One title in 1972 on the final day of the season! So that didn’t go down well. Especially as it consigned Leeds to the 2nd place (runners up) for the third consecutive season. Oh dear.
The two Managers always had a bitter war of words, both in respective local media and on national TV too.
Cloughie was in particular quite scathing in his attacks, branding Leeds & Revie’s style of play as ‘dirty’ and ‘cheating’.
Whenever the two teams played each other, the games would always have an edge to them, turning violent & hostile. This applied to the players on the pitch and the two sets of fans as well.
Then when Revie went on to be the next England Manager, Cloughie replaced him at Leeds Utd for the infamous 44 days in charge in 1974!
Revie subsequently failed as England Manager whereas Cloughie went on to lead the red-dogs down the A52 to two European Cups.
More recently there was the Bielsa ‘Spygate’ incident in 2018 (I think) where, before an upcoming game he sent someone to peep thro the bushes on the main road outside our training ground,watching our team train & possibly tactics too. Lol. Ya couldn’t make it up.
HTH a bit?