In 1913 he graduated from the College for aeronautical engineering. During the first world war , he developed a new type of propeller, which allowed better performance than the common types. He called this the "Hélice Eclair" and together with another aviation pioneer, Henry Potez, he founded the "Société des Hélices Eclair". In 1917, they formed, along with a third friend, the "Société d'Etudes Aéronautiques" (SEA) with the intention to build own aircraft. The first airworthy model was the two-seater SEA 4, of which the French Ministry of war thousand copies ordered. When the supply could start however the war was over and was cancelled the order; only a hundred copies to which was already built, were delivered. Thereupon pulled Bloch out the aviation and went into the real estate.
When in 1928 the French Air Ministry was founded, Bloch returned back to the aircraft industry and founded the "Société des Avions Marcel Bloch" on the second against 1935 grew from this largest aviation company in France. In 1936 the company was nationalized and housed in the "Société nationale de constructions aéronautiques du Sud-Ouest" (SNCASO), of which he was the Managing Director. A few months later he began a new company, the "Société anonyme des avions Marcel Bloch" (SAAMB). In this he developed prototypes of new aircraft, of which the series construction by the State-owned French aviation industry happened: the SNCASO built as in the single-engine fighter aircraft series MB 150, the two-engined bomber MB 170, and a four-engine passenger plane, the MB 161. The MB 174 (1939) was a single-enginereconnaissance aircraft that would be used by Antoine de Saint-Exupéry.
After the outbreak of the Second World War in 1940 he was arrested by the VichyGovernment. He refused to collaborate with the occupier and eventually ended up in Buchenwaldin 1944, from which he was released after eight months.
In 1949 he changed his family name in Dassault; This was the code name that his brother, Paul Bloch, General in the resistance during the war used. In that year flew the MD 450 Ouragan, the first jet aircraft of Dassault. In 1952 followed the Mystère III and Mystère IV; in 1956 the Étendard IV (for the aircraft carriers of the French Navy) and the Mirage III, which would be sold to many countries, including Israel and (in a later version Mirage V) to Belgium. In 1959 came the Mirage IV bomber for the French nuclear "Force de Frappe". Most recent Dassault combat aircraft are Mirage 2000 and Rafale .
In the Dassault civil aviation is best known for its Falcon business jets, of which there are different versions released since 1970. A large passenger plane, the Mercure (1971) was not a success; only 12 were built .
The "Société des Avions Marcel Dassault", later "Dassault Aviation" grew into a large military-industrial conglomerate. In 1981 it was nationalized, but Dassault remained the company lead to his death.
Dassault was still active in other areas. He founded a weekly magazine on, "Jours de France", "Paris-Match" competitor, and took care of it itself the section "le café du commerce". He also produced some films (La Boum 2 (1982) with Claude Brasseur; Jamais avant le mariage (1982); La septième CAL (1984) with Lino Ventura; Les parents ne sont pas simples cette année (1984)) and also possessed own cinemas at the ParisChamps Elysées.
He received the highest French award, the Grand Cross of the Legion of honour.
The company put his son Serge Dassault Dassault on.