Adolph Schild, formerly associated with Eterna, began producing watch movements Grenchen, Solothurn after 1896. Schild produced many different movements and became one of the largest movement makers in Switzerland by the 1920's.
In 1926, ASSA was combined with A. Michel AG (also of Grenchen) and Fabrique d' Horlogerie de Fontainemelon (FHF) (of Fontainemelon) to create Ebauches SA. Each component company maintained independence and branding, but the combined entity was able to weather the difficult economic conditions of the depression and World Wars and rose to dominate Swiss movement manufacturing. A. Schild would become part of ASUAG (along with Eterna) in 1931.
After 1939, A. Schild movements were identified by a stamped marking featuring a shield with the letters "AS" inside. A. Schild movements were used by many manufacturers in the 1950's through 1970's, including such familiar names as Harwood, Fortis, Enicar, and even Jaeger-LeCoultre.
The quartz crisis of the 1970's hit A. Schild especially hard, as inexpensive Japanese and quartz watches cut into the market for volume-produced three-handed watches. By 1979, Ebauches SA, including A. Schild, was merged with ETA (also of Grenchen) to survive. ETA had been formed by Eterna after the departure of Adolph Schild, so this merger was a historic reunion of Schild family movement-making.
A. Schild movements are greatly respected today for their reliability, and many new old stock pieces remain in use. Indeed, manufacturers like Alexander Shorokhoff and Favre Leubra continue using A. Schild ebauches in new watches.