Early products were marked "MGR" (for Mayer, Grammelspacher and Rastatt) before the introduction of the now-famous "Diana" brand name.

The popularity of shooting as a leisure activity prompted development of a range of children's toy guns (firing arrows tipped with suction cups) under the Eureka brand.

[2] The Second World War stymied Diana's early success, with sanctions imposed on the Nazi government severely limiting export opportunities.

By 1940 civilian production was halted and the factory was commandeered to produce parts for Mauser, which led to heavy Allied bombing.

The occupying forces decommissioned the factory and sold the company lock, stock and barrel to England's Millard Brothers (Milbro), who moved production to Scotland.