Through the second half of the 1930s motor racing was dominated by two German teams - Auto Union and Mercedes, known collectively as the Silver Arrows - who benefited from state funding from the Nazi regime. They were almost unstoppable, in effect crushing all viable opposition.

The Silver Arrows drivers were stars in Germany, and the vehicles they drove were propaganda vehicles, unashamedly adorned with swastikas even if not all of those behind the wheels endorsed the Nazi ideal. Despite that, the value of their success to Hitler was unquestionable.

The 1939 season followed a similar pattern to earlier ones. The Silver Arrows swept all before them in the major races, leaving the other marques to battle for the scraps in the less important contests.

By the time of the Swiss Grand Prix in August - the fourth and final race counting towards the European championship - much of Europe was preparing for a war which seemed inevitable. Hermann Lang's victory, completing the Silver Arrows' clean sweep, gained him the drivers' title, albeit in controversial circumstances. According to the rules at the start of the season, Hermann Müller should have won on points, but Herman Lang had more wins and was favoured by the Nazis.

On August 25 the Mercedes team set out on a 1400km journey to Belgrade, taking with it a large fuel lorry as a precaution in case it had to get back to Germany under its own steam. It entered two cars, as did Auto Union, partly an indication that the race was not among the most important and partly a sign that even the teams were not oblivious to the deteriorating political situation around them.

von Brauchitsch prepares for the start of the race © Unknown Enlarge

Lang travelled with the Mercedes team and his team-mate Manfred von Brauchitsch arrived in Belgrade by air from Munich on August 31. A cursory inspection of the proposed 3km course was not encouraging - it was undulating with numerous cobbles and tramlines. In the practice session that evening Lang was fastest out of the three cars that took part.

The Germans noted the atmosphere was tense in the city and chose to stay in their hotel, although the Mercedes drivers did venture out for a stroll. Early the next morning drivers and officials were woken early by reporters to be told German troops were attacking Poland. Lang recalled driving up to a nearby hill, where radio reception was best, to listen to the news. Emotions were mixed but the organisers pleaded with the Silver Arrows to stay; had they not then the financial losses would have been substantial.

The decision was not actually in their hands. Adolf Hühnlein, a high-ranking Nazi official who headed the National Socialist Motor Corps, who controlled German motorsports, ordered them to remain and race to underline German dominance.

As Auto Union were still waiting for Tazio Nuvolari, Ulrich Bigalke joined Müller on the second day of practice, taking the number of cars to four - Alfa Romeo and Maserati, which were tentatively expected, never materialised and the British had been told earlier in the month European travel was unadvisable.

Although Nuvolari finally arrived in Belgrade by train on the Saturday for qualifying, he was understandably off the pace against three drivers who were now familiar with the circuit, even though he had been favoured with a special practice session earlier in the day. Even von Brauchitsch was faster although an Auto Union official noted he was "still drunk from the previous evening".

Lang in action before shattered goggles forced him out © Unknown Enlarge

On the morning of the race - Sunday, September 3 - things grew even more serious with the news Britain had declared war on Germany. Lang remembered hearing the news at breakfast. "All of us lost every inclination to race but [Alfred] Neubauer [the Mercedes manager] returned from our embassy with the news we must keep calm and start."

But shortly after dawn, von Brauchitsch set off for the airport and bought a ticket on a flight to Vienna. On hearing the news a furious Neubauer immediately went after him, hauled him off the plane and ordered him to compete.

Against this backdrop a series of races took place in the morning - three for motorcycles and four for sports cars - ahead of the main event. Five cars assembled on the grid; two each from Auto Union and Mercedes and one local entry, Bosko Milenkovic in an old 2.3-litre Bugatti T51. Milenkovic did not feature in any of the practices and appears to have only joined the others on the day.

At 4.45pm in warm late-summer sunshine the race started in front of between 75,000 and 100,000 spectators. von Brauchitsch got the better start from Lang, with the Auto Unions in third and fourth - Milenkovic was woefully slower than the others and by the end was more than 19 laps adrift.

Lang and von Brauchitsch were tearing into each other, ignoring Neubauer's frantic signals to race as a team. On the seventh lap a stone from von Brauchitsch's car flew up and hit Lang. "Suddenly something hit me and everything went dark," Lang said. "[It] not only shattered my autoscreen but also both glasses in my goggles. My eyes were full of splinters." He managed to get to the pits, blood streaming down his face, and the Mercedes team doctor pulled glass splinters from his eyes while Walter Bäumer took over his car.

On the 16th lap von Brauchitsch spun and stalled. "My engine died and I had to let the car run backwards so that it would start again." As he turned it round "Nuvolari came round the corner like a shadow… thanks to his extreme driving skills an accident was avoided." von Brauchitsch's bullying driving continued, forcing Bäumer into the straw bales and out of the race, but into the second half the rough surface started taking a toll. Milenkovic had a lengthy stop because he was unable to remove his radiator cap, while von Brauchitsch came in with destroyed tyres, soon followed by the leader, Nuvolari. But Nuvolari returned with the aid of a push from his mechanics, another rule violation which was spotted by Mercedes. Neubauer was about to lodge a protest when he was quietly reminded about von Brauchitsch's own indiscretion.

Nuvolari climbs out of his Auto Union after winning © Unknown Enlarge

After 65 minutes and 50 laps the race was over. Nuvolari won by 7.6 seconds from von Brauchitsch with Müller a further 23 seconds behind. Milenkovic, still pottering around, was flagged in. The Prince Regent, Paul, presented Nuvolari with the cup of King Peter II. It was the last win of Nuvolari's brilliant career.

There were no celebrations. News had arrived during the final laps that France had declared war on Germany, and the two teams wanted to return home as soon as possible. Mercedes went avoiding Hungary after reports their fuel lorry would be confiscated, even going so far as to split up to make detection harder. Auto Union, who had taken the precaution of buying up fuel of their own locally, took a different - and unknown - route.

The journey took the teams four days, but there was a final twist to the Belgrade Grand Prix. Even though Europe was at war, Mercedes and Auto Union continued to exchange letters about the illegal moves of their two drivers.

That was the last grand prix in Europe for almost seven years and the end of a remarkable era. The Nazi party continued to fund the Silver Arrows until 1941and senior party officials sought to keep racing going through 1940 in safe territories. But as the war escalated it was increasingly evident normal racing was not a feasible option as the resources needed to maintain the teams could not be justified.

The last contest, the Mille Miglia, took place on April 28, 1940 and was won by Huschke von Hanstein and Bäumer. The photo of the wining pair shows them resplendent in Nazi insignia, although the propaganda machine had to doctor the picture and add the SS logo to Bäumer's overalls.

The Belgrade Grand Prix also fell victim to politics as it was all but airbrushed out of the record book by Yugoslavia's communist government, partly because of the role of King Peter and partly because the race was dominated by drivers from fascist countries.