" It was about practice, practice, practice (for they knew not what). Then, on the day, it was about the constant monitoring of data–glide paths, magnetic compass deviations, dead reckoning pinpoints, calculations of fuel according to atmosphere and so on. These men were not just beefy brave chaps; they had real brains. Lancasters cannot take off at night in formation and fly low for hundreds of miles, drop an enormous bomb that is spinning at 500 revolutions per minute from exactly the right height and then move on to another target before returning home–all the time under fire from enemy anti-aircraft batteries–without a particular kind of steady, unblinking courage, tenacity and will that is out of the ordinary. "

― Andrew Roberts , The Storm of War: A New History of the Second World War