On 6 August 1941, "Kongō Maru" was requisitioned by the Imperial Japanese Navy and was converted to an armed merchant cruiser at the Harima Shipyards at Aioi. Single mount &lt;a href="14%20cm/50%203rd%20Year%20Type%20naval%20gun"&gt;14 cm/50 3rd Year Type naval gun&lt;/a&gt;s were installed at her bow and stern, as were two Type 93 13.2-mm machine guns and two torpedo tubes. Her conversion was completed on 14 October and she was assigned to the IJN 4th Fleet’s "South Seas Force" and deployed to Truk. At the time of the attack on Pearl Harbor, "Kongō Maru" was at Kwajalein, from which she deployed as part of the Japanese task force in the first attempt to invade Wake Island on 8 December 1941. She was bombed by USMC F4F Wildcat aircraft using depth charges, and caught fire. The fires were brought under control and she returned to Kwajalein. She later participated in the second attack on Wake Island on 21 December 1941, which succeeded in taking the island. After the battle, "Kongō Maru" was sent via Saipan, Truk and Guam to participate in the battle of Rabaul on 22 January 1942.