In F1, after his promising start the previous year, 1966 was a poor year for Stewart; the 3-litre H16 BRMs were unreliable, although Stewart did win the Monaco Grand Prix in a 2-litre engined car. The most significant event in that year was his accident at the Belgian Grand Prix at Spa-Francorchamps, which sparked his campaign to improve safety in F1 and caused him to miss the French Grand Prix at Reims.