Jackie Stewart won the German Grand Prix for Matra in what years later he said was possibly his greatest drive. The conditions were truly appalling - it had been raining for three days and there was dense fog hanging over the already-dangerous Nürburgring. He also had his right wrist and hand in a special plastic cast after an accident a few months earlier.
So bad was the rain that the organisers scheduled an additional practice session on the Sunday - Saturday was abandoned with visibility down to ten yards - but the conditions did not improve and several drivers slid off in the morning.
The start of the race itself was delayed by 50 minutes, but all that happened was the fog grew denser and the rain heavier. Around 200,000 spectators trudged to the circuit to watch but few could have seen more than silhouettes speeding past them in the gloom. So unusual were conditions that Jacky Ickx on pole had qualified a full minute ahead of Stewart in sixth, but Ickx suffered wheel spin at the off and by the first corner Stewart was up into third behind Graham Hill and Chris Amon.
"Visibility is so pathetically poor I can't even see Chris' car in front of me," Stewart wrote in his autobiography Winning Is Not Enough. These were the days before rear lights for use in bad weather. "I am simply driving into this great wall of spray. I pull out to pass him but the spray is dense and I'm driving blind."
He passed Amon and then Hill - and this was all on the first lap - but the ordeal for the drivers was constant as water formed streams across the track causing the cars to aquaplane. It was a demonstration of brilliant wet-weather driving which ultimately pulled him some four minutes clear of the rest of the field.
Hill and Amon conducted their own battle for second, rarely separated by more than a second or two for 11 of the 14 laps until Amon spun off attempting to overtake. As he walked back to the pits - which were also awash by this time - he was warmly applauded by the crowd.
Hill was out alone but he too span off and also stalled. He got out of the car and managed to push start it, jumping back on-board and resuming the race. But the delay had allowed Jochen Rindt to close, and the last lap was a bitter battle which Hill edged by four seconds. Afterwards Stewart admitted "it was a teeth gritting effort" but it had brought him within three points of Hill at the top of the championship.