The marriage of the star and the wreath.

The idea was old. DMG's own board had explored a union during the First World War and got nowhere. On paper it was obvious: two firms in the same corner of south-west Germany, building the same thing, descended from Carl Benz in Mannheim and Gottlieb Daimler in Cannstatt — two men who invented the automobile within months of each other and never once met.

In 1919 it was Benz & Cie. that proposed the merger outright. DMG formally turned it down that December. Both companies were emerging from a lost war into a collapsing currency, and both preferred the risk of dying alone to the certainty of sharing a boardroom.

What stood in the way was not engineering but banking. The Württembergische Vereinsbank held a seat on DMG's supervisory board and had no intention of letting the Rheinische Creditbank, which sat on Benz's, anywhere near Untertürkheim. The deadlock broke twice over: first when the Vereinsbank's representative died, and then when both banks were swallowed by Deutsche Bank, which now held stakes in both carmakers and no reason whatever to keep them apart.

By then the arithmetic had turned brutal. The 1923 hyperinflation had hollowed out both balance sheets; measured in gold marks, one account of the period says, what the two companies were actually worth spoke eine traurige Sprache. Germany's oldest and proudest manufacturers were, separately, too small to survive their own market.

The fighting started at the syndicate's very first joint board meetings, in May 1924, and it was about a two-litre car. DMG intended to build a small supercharged six — around 40 hp, 60 with the blower engaged — in Benz's own plant at Mannheim. Friedrich Nallinger of Benz doubted a complex, expensive supercharged car could keep the Mannheim workforce employed, and pointed out that Benz had already finished designing a simpler naturally aspirated two-litre with a swing axle.

By November 1924 it had escalated. Mannheim argued that the Untertürkheim design did not suit its tooling and would make production slower and dearer, and that the projected price of RM 15,000 was fantasy at the volumes involved — around 500 cars a month.

Underneath the tooling argument was a disagreement about what a car was for. Benz wanted to sell a great many cars cheaply. DMG wanted to sell technically sophisticated cars expensively. The syndicate had merged the balance sheets without merging the strategy.

A compromise appeared in January 1925: Benz would build a 2.6-litre side-valve car instead, while DMG finished the overhead-valve two-litre for later. In January 1926 the board enlarged the 2.6 into a three litre, which appeared that October as the 12/55 PS.

And then Benz turned out to have been right. When the two-litre was restarted in the summer of 1925 it was rebuilt around its price. In September the open tourer was to cost RM 10,000; by January 1926 the target was RM 6,500, less than half what the supercharged original would have asked. Stripped of the blower and the ambition, it became the 8/38 PS — the car that carried the merged company.

It worked, and it worked fast. Production of the two-litre reached 270 cars a month by March 1927, and in that year it alone sold more than twice as many cars as every Mercedes, Benz and Mercedes-Benz built in 1926 put together. The cheap car Mannheim had insisted on paid for everything that followed.

In February 1928 the company tidied up its names. To the old fiscal-horsepower designations it added a three-digit number giving the engine's rounded displacement in tens of cubic centimetres, and the 8/38 PS became the 8/38 PS 200. That number never went away.

Then the cars started taking place names. The Nürburg 460 arrived in October 1928, called after the Nürburgring because that is where it had been endurance-tested. A month later the facelifted two-litre became the Stuttgart 200. A year after that the three litre, by now 3.5, became the Mannheim 350. Stuttgart and Mannheim, the two towns that had spent 1924 trying to overrule each other, ended up as trim names on the same price list.

The engineering caught up last. Through the syndicate years the design department had been split in two, Hans Nibel running Mannheim and Ferdinand Porsche running Untertürkheim, formally as equals. Nibel — Benz's chief engineer, and an advocate of full merger throughout — had already directed the 1928 facelift that produced the Stuttgart.

On 1 January 1929 he became technical director in Porsche's place, and for the first time one man held sole responsibility for what the company built. What followed under him was the 770 Großer Mercedes, the 170, the first six-cylinder diesel for trucks, and eventually the W 25 Silver Arrow.

The empty chair took longer. Wilhelm Kissel had joined Benz & Cie. as a correspondence clerk in 1904, worked his way into purchasing, and organised the 1924 syndicate; he sat on the merged board from the start. He began chairing its meetings in 1930, but he was only formally made chairman on 1 October 1937 — a new German company law created the post. He held it until his death in July 1942.