Southern Expeditionary Army Group The was an army group of the Imperial Japanese Army during World War II . It was responsible for all military operations in South East Asian and South West Pacific campaigns of World War II . The Southern Expeditionary Army Group was formed on November 6 , 1941 , under the command of " Gensui " Count Terauchi Hisaichi , with orders to attack and occupy Allied territories and colonies in South East Asia and the South Pacific . Operational history . The Philippines . Plans for an invasion of the Philippines were finalized on November 13 – 15 , by Lt General Masaharu Homma , Lt General Hideyoshi Obata , Vice Admiral Ibō Takahashi and Vice Admiral Nishizo Tsukahara . These plans called for air attacks against the Philippines , beginning on " X - Day " , by the 5th Army Air Force Division and the 11th Naval Air Fleet . At this time , Imperial Japanese Army and Imperial Japanese Navy units were to land on Batan Island , Luzon ( at Aparri , Cagayan , Vigan , and Legazpi City ) , and at Davao , Mindanao , and to seize airfields . Following the elimination of American air support , the main body of the IJA 14th Army was to land at Lingayen Gulf , while another force landed at Lamon Bay . These forces were then to attack Manila in a pincer attack . After this , the islands of Manila Bay were to be taken . In the resulting Battle of the Philippines ( 1942 ) , Japanese forces accomplished their primary objectives . French Indochina . On July 22 , 1941 , Japanese forces invaded Vichy French Indochina and occupied its naval and air bases . Netherlands East Indies . On January 18 , 1942 , the commander of 16th Army Lt . General Hitoshi Imamura arrived at Takao , Taiwan from his base at Saigon . He received an order to hasten the invasion preparation toward Java . But due to shipping shortages , he had to adjust the plans . On January 21 , he arrived at Manila to inspect the IJA 48th Division and to have discussion with the commander of the IJN 3rd Fleet . The Netherlands East Indies was invaded in a three - prong attack by using 3 groups : western , center and eastern group . Western invasion group . The IJA 2nd Division of the IJA 16th Army , which was assembled in Taiwan , was ordered on January 25 to move in to Cam Ranh Bay and became the main force of western invasion group . At Cam Ranh Bay , the troops were trained for the tropical jungle warfare . On the 30th , the attack order was announced . The western group was carried aboard 56 transport ships and left for Java on February 18 . By midnight on February 28 , the ships landed at Merak and Bantam Bay on Java island . Following the surrender of Hong Kong , the 228th , 229th and 230th Infantry Regiments from the IJA 38th Division were also deployed to Netherlands East Indies separately . On February 13 , the 229th and 230th assaulted Palembang on Sumatra and then joined the main force . On February 28 midnight the 230th Infantry Regiment landed on Eretan Wetan on Java . Center invasion group . The center group was composed of IJA 48th Division , left for Java on February 8 , 1942 from Lingayen Gulf , in the Philippines . On February 25 , the convoy arrived at Balikpapan and the Sakaguchi detachment ( 56th Regiment Group ) joined the force . They landed at Kragan on Java by midnight February 28 . Earlier on January 11 , the Sakaguchi detachment and 2nd Kure Special Naval Landing Force occupied Tarakan . They secured Balikpapan on January 23 . On 10 February Bandjermasin , the capital of Dutch Borneo was occupied . Eastern invasion group . The Eastern invasion group included the Sasebo Combined Naval Landing Force and 1st Yokosuka Special Naval Landing Force . They left Davao on January 9 and during the early morning of January 11 , arrived at and occupied Menado . The Sasebo Combined Special Naval Landing Force then attacked and occupied Kendari on January 23 . Makassar was captured on 9 February by the Sasebo Combined Special Naval Landing Force . All these are on Celebes island . The 1st Kure Special Naval Landing Force and 228th Infantry Regiment from 38th Army and Airplane Carrier Division 2 from Japan , reached Ambon on January 30 .