In 1936, further orders were placed for Fairey to build additional Battles to Specification P.14/36. In June 1937, the first production Battle, "K7558", conducted its maiden flight. "K7558" was later used to perform a series of official handling and performance trials in advance to the wider introduction of the type to operational service. During these trials, it demonstrated the Battle's ability to conduct missions of a 1,000-mile range while under a full bomb load. The first 136 Fairey-built Battles were the first to be powered by the Merlin I engine. By the end of 1937, 85 Battles had been completed and a number of RAF squadrons had been re-equipped with the type, or were otherwise in the process of re-equipping.