Why was the 'bodyline' bowling technique invented?

England devised the 'bodyline' bowling tactic to counter Don Bradman's batting, during their Australia tour for the 1932-33 Ashes. The tour, which started on December 2, 1932, came to be known as the Bodyline series for its controversial bowling tactics. Bodyline involved bowling short, fast-pitched deliveries on the line of leg stump, which were physically threatening for the batsmen.