The Longbridge car plant was part of a significant rapid mobilisation process which took place across Europe on the outbreak of World War I. Machines that had been used to build Austin cars were employed to produce munitions, and all the resources of the factory were harnessed to serve the armed forces.
As the demand for weapons and equipment of every kind continued to increase, the factory was expanded. The area between the existing buildings and the Midland Railway mainline were built on. The expansion also enabled the 1915 construction of Longbridge railway station within the boundaries of the works, allowing the Midland Railway to run workers trains direct from Birmingham New Street.