AW Mark 1, an air-warning system for the Australian Air Force. These both operated at 200 MHz (1.5 m). War on Japan began in December 1941, and Japanese planes attacked Darwin, Northern Territory the following February. The New South Wales Railways Engineering Group was asked by the RPL to design a lightweight antenna for the air warning radar, also known as the Worledge Aerial. LW/AW Mark I. From this, the LW/AW Mark II resulted; about 130 of these air-transportable sets were built and used by the United States and Australian military forces in the early island landings in the South Pacific, as well as by the British in Burma. American troops arriving in Australia in 1942–43, brought many SCR-268 radar systems with them. Most of these were turned over to the Australians, who rebuilt them to become Modified Air Warning Devices (MAWDs). These 200-MHz systems were deployed at 60 sites around Australia. During 1943–44, the RPL involved a staff of 300 persons working on 48 radar projects, many associated with improvements on the LW/AW. Height-finding was added (LW/AWH), and complex displays converted it into a ground-control intercept system (LW/GCI). There was also a unit for low-flying aircraft (LW/LFC). Near the end of the war in 1945, the RPL was working on a microwave height-finding system (LW/AWH Mark II). Canada Of the four Commonwealth Nations, Canada had by far the most extensive wartime involvement in radar. The major responsibility was with the National Research Council of Canada (NRCC), specifically its Radio Branch headed by John Tasker Henderson. Their first effort was in developing a surface-warning system for the Royal Canadian Navy (RCN) to protect the Halifax Harbour entrance. Called Night Watchman (NW), this 200-MHz (1.5-m), 1-kW set was completed in July 1940. In September 1940, on their trip to the United States for cooperative exchanges, the Tizard Mission visited Canada and recommended that Great Britain use Canadian personnel and facilities to supplement the British programs. Research Enterprises, Ltd. (REL), was then established to manufacture radar and optical equipment. The next system was a ship-borne set designated Surface Warning 1st Canadian (SW1C) for corvettes and merchant ships. The basic electronics were similar to the NW, but it initially used a Yagi antenna that was turned using an automobile steering wheel. It was first tested at sea in mid-May 1941. The project engineer from the NRCC was H. Ross Smith, who remained in