War Department created four armies to control the field forces. This left the corps areas with administrative responsibilities only. The corps areas were renamed service commands on 10 July 1942. The new title reflected their status as administrative and supply agencies. Somervell saw them fulfilling the role of field agencies of the ASF. Army installations in the continental United States were divided into four categories. Class I installations were ASF installations, which were placed directly under the service commands; Class II installations were posts and stations of the Army Ground Forces; Class III installations were Army Air Forces bases; and Class IV installations were those which, on account of their technical nature, remained under the direct command of a chief of a technical or administrative service. These included the GOGO manufacturing plants, proving grounds, procurement offices and the ports of embarkation. Class I installations included recruiting stations, induction and reception centers, repair shops, enemy alien and prisoner of war camps, medical and dental laboratories, Reserve Officers' Training Corps (ROTC) units, dispensaries except for the General Dispensary in Washington, DC, finance offices, disciplinary barracks and named general hospitals except for Walter Reed General Hospital. The boundaries of the service commands and the location of their headquarters were not changed, and they remained the same throughout the war with one exception. The Military District of Washington (MDW) was created in May 1942. It included the District of Columbia and Arlington County, Virginia. In August 1942 it was separated from the Third Service Command and assumed the status of a service command, except that its commander also served as the headquarters commandant for the War Department, and as such also reported to the Deputy Chief of Staff of the Army. The MDW was enlarged in December 1942 to include Fort Washington and Fort Belvoir. One additional service command was created: the Northwest Service Command, in September 1942, with its headquarters at Whitehorse in the Canadian Yukon Territory. It was responsible for the construction and maintenance of the Alaska Highway, the operation of the railway between Skagway, Alaska and Whitehorse, and the Canol Project. It was abolished on 30 June 1945, and its responsibilities were transferred to the Sixth Service Command. On 31 July 1943, 751,911 personnel were assigned to the service commands, representing 45 percent of the ASF. The idea of a unified command of many arms and services was a familiar one