Nothing is known about his prior military service although he was 23 when the war started.
It is known that he flew with Jastas 2 ( Boelcke) and 27 in France and Flanders. His first confirmed victory was on 11th April 1917 - a Spad VII - and 30 of his victories were achieved during 1918 with the ultimate - a Bristol F 2B - falling to his guns just a week before the Armistice..
He was never awarded the PLM despite his high number of victories.
Frommherz survived the Great War.
Confirmed victories
| Aircraft Manufacturing Co | Airco DH 9 | 2 |
| British & Colonial Aeroplane Co | Bristol F 2B | 6 |
| Royal Airforce Factory | RAF BE 2e | 1 |
| Royal Airforce Factory | RAF RE 8 | 3 |
| Royal Airforce Factory | RAF SE 5a | 3 |
| Société Anonyme des Etablissements, Nieuport | Nieuport 28 | 2 |
| Société S.P.A.D. | Spad S VII | 3 |
| Société S.P.A.D. | Spad S XI | 1 |
| Société S.P.A.D. | Spad S XIII | 1 |
| Sopwith Aviation Co | Sopwith ? | 1 |
| Sopwith Aviation Co | Sopwith Camel | 8 |
| Sopwith Aviation Co | Sopwith Dolphin | 1 |
| Total | 32 |
