Although vehicles that incorporated the basic principles of the tank armour, firepower, and all-terrain mobility had been projected in the decade or so before the War, it was the alarmingly heavy casualties of the start of its trench warfare that stimulated development. Although initially termed "Landships" by the Landships Committee , production vehicles were named "tanks", to preserve secrecy. The term was chosen when it became known that the factory workers at William Foster referred to the first prototype as "the tank" because of its resemblance to a steel water tank. The French fielded their first tanks in April and ultimately produced far more tanks than all other combatants combined. The Germans , on the other hand, began development only in response to the appearance of Allied tanks on the battlefield.