 Complete the following phrase:  The barrel of the original prototype, known as Mother is preserved on a Mk I carriage by the Imperial War Museum. This howitzer was tested at Rhayader in Powys, Wales in July 1914. Sent to France, it was operated by 8th Siege Battery from October 1914. The howitzer was visited by Field Marshal Sir John French on 5 November 1914 and by the Prince of Wales on 18 November. Transferred to 10th Siege Battery in early 1915 it saw use during the battles of Neuve Chapelle in March 1915 and 