Merz was a works Mercedes driver for many years, though not one of the better known ones. He had been chauffeur to Archduke Ferdinand of Austria and indeed, it was Merz who was driving the Archduke's Austro-Daimler on the June 28th, 1914 when he was assassinated in Bosnia and event that triggered the First World War.
In 1906 Merz went to work for Daimler as a mechanic, working his way up to become mechanic for Theodor Dreher and Willy Pöge. He was huge and had a reputation of being something of a hard man and could apparently drive a six inch nail into a piece of wood with his bare fist. It was probably this reputation that led him to work as a chauffeur come bodyguard to Archduke Ferdinand of Austria and indeed, it was Merz who was driving the Archduke's Austro-Daimler on the June 28th, 1914 when he was assassinated in Bosnia.
Merz drove the archduke and his wife, Sophie, drove into Sarajevo, but as they crossed the Milijacka River at Cumuria Bridge, a Serbian nationalist named Nedjelko Cabrinovic threw a bomb at their car. Franz Ferdinand managed to deflect the bomb onto the street and about a dozen people, including his wife, were injuried, though there were no fatalities. Cabrinovic swallowed a cyanide pill and jumped off the bridge. Unfortunately for him, he coughed up the pill, landed in only a foot of water and was taken into custody.
The Archduke then continued to Sarajevo City Hall where he made a speech. Afterwards he got Merz to drive him to the hospital to visit the victims of the bomb. Unfortunatly the lead car in the motorcade took a wrong turn and ended up on a street named after Franz Ferdinand’s father, Franz Josef. Noticing the mistake they stopped but they were only inches from another Serbian nationalist, Gavrilo Princip.
Princip was a member of Young Bosnia and one of many assassins organized by The Black Hand to kill Franz Ferdinand. Princip fired a pistol into the car, hitting the Archduke in the neck and his wife in the stomach. Merz carried the Archduke into a nearby house to try to protect him but his wound was fatal.
Though a lengthy investigation failed to prove any complicity on the part of the Serbian government, the Austrians sent their army into Serbia and World War I began.
Merz started competing after the war as riding mechanic before becoming a works Mercedes driver. He did wel in hill-climbs and in 1924 set the fastest time at both Solitude and Klausen. He also set the fastest time in the 1Km speed trial in Geneva in 1926 driving a Mercedes 24/100.
His real moment of glory came in 1927. The Nürburgring had opened on 19th June with Caracciola taking the win. Then a month later the circuit hosted the German Grand Prix. Merz won when Caracciola broke down. Merz covered the 316.1 miles in 4 hours, 59 minutes, averaging 63.31 mph. Christian Werner and Willy Walb finished 2nd and 3rd, also in Mercedes. Finishing 4th was Elizabeth Junek of Czechoslovakia in a Bugatti.
After that he only participated in few races like the 1928 German Grand Prix, finishing 2nd and the 1929 TT in Ireland with Caracciola. During the TT their Mercedes damaged a fender. Otto, with typical directness, promptly tore off the fender with his bare hands and continued to race sadly only to be disqualified.
He was usually used as a reserve or test driver, but he did compete in the ADAC long distance trials. In 1931 he shared Caracciola's Mercedes SSKL in the French GP and, on his own, came fifth in the German GP. Mercedes withdrew from racing the following season and while Otto did not race during 1932, Caracciola left Daimler-Benz and went to Alfa Romeo.
Following a year off, Otto entered 1933 the Avusrennen with a specially built streamlined SSKL at the 1933 Avusrennen. von Brauchitsch was there in another SSKL. During the first practice on Thursday, May 18, 1933, in the wet, Otto Merz was killed when the car skidded and rolled. The crash was probably caused by faulty aerodynamics making the car unstable.