Simonds knew that infantry assaults supported by massed artillery had failed to overcome the German forward lines in Operation Atlantic and Operation Spring. During Operation Goodwood, a bombardment by aircraft of RAF Bomber Command had assisted British tanks to break through the German front but they had then suffered many casualties from intact German defences arrayed in depth beyond the bombing. Infantry had been unable to follow up quickly enough to support the leading tanks or to secure ground behind them (so that follow-up units were also slowed). To solve the tactical problem presented by the terrain and the deep defences, Simonds proposed a radical solution, the first large attack by mechanized infantry.