the prevention of an orderly withdrawal to the south by Japanese forces. Once troops from the 1st Far East Front and Trans-Baikal Front had captured the city of Changchun, the 2nd Far East Front was to attack the Liaotung Peninsula and seize Port Arthur (present day Lüshun). Japanese The Kwantung Army of the Imperial Japanese Army, under General Otozō Yamada, was the major part of the Japanese occupation forces in Manchuria and Korea and consisted of two Area Armies: the First Area Army (northeastern Manchukuo) and the Third Area Army (southwestern Manchukuo), as well as three independent armies (responsible for northern Manchuria, North Korea, Mengjiang, South Sakhalin, and the Kurils). Each area army (Homen Gun, the equivalent of a Western "army") had headquarters units and units attached directly to it, in addition to the field armies (the equivalent of a Western corps). In addition was the 40,000-strong Manchukuo Defense Force, composed of eight weak, poorly-equipped, and poorly-trained Manchukuoan divisions. The combined forces of the Kwantung Army in Manchuria and the Seventeenth Area Army in Korea came close to one million men. The two armies had no fewer than 31 divisions and 13 brigades (including two tank brigades) between them, together with numerous separate regiments and fortress units. In Manchuria alone there were approximately 700 armored vehicles and 5,000 guns and mortars (excluding 50 mm grenade dischargers), while the Japanese Air Forces had 2,004 planes in Manchuria and Korea, of which only 627 were combat types. The Imperial Japanese Navy did not contribute surface forces to the defense of Manchuria, the occupation of which it had always opposed on strategic grounds. Additionally, by the time of the invasion, the few remnants of its fleet were stationed in defense of the Japanese home islands in anticipation of a possible invasion by Western Allied forces. Despite its large size, the Kwantung Army was badly trained, poorly equipped, and had only limited supplies: overall ammunition stockpiles were sufficient to meet the needs of only 13 divisions for 3 months, compared with 24 divisions then in Manchuria. Most of its heavy equipment and all of its best troops had been transferred to the Pacific Front over the previous three years, with second-rate units raised to replace them. As a result, it had essentially been reduced to a light infantry counterinsurgency force with limited mobility or ability to fight a conventional land war against a co-ordinated