Rear-Admiral Kenzaburo Hara was in November 1941 Commander of Destroyer Squadron 5 with light cruiser Natori (flagship) and Destroyer Divisions 5 and 22 (eight destroyers).

He commanded the First Surprise Attack Force for Aparri (Philippines) landings in December 1941 and he was also Commander of Third (Close) Escort Force for Western Force with light cruisers Yura and Natori and sixteen destroyers for the invasion of Java, February 1942.

His assignments in the first period of war were:

- First Phase (December 1941): he commanded No. 1 Kyu Shutai (Surprise Attack Unit) of Philippine Force at Aparri (10 December 1941) and at Lingayen (22 December 1941) landings

- Second Phase (January - February 1942): he commanded No. 2 Goeitai (Escort Unit) of Malay Force of 3rd Malay Convoy (8 January 1942)

- Third Phase (February - March 1942): he commanded No. 3 Goeitai (Escort Unit) during Dutch East Indies Campaign when he led (west) convoy escort during landing in Bantam Bay (1 March 1942) on West Java