In 1942, the Japanese invaded the Dutch East Indies, arriving in Sumatra by February. Sumatra was placed under the command of the 25th Army, based in Singapore. Following the surrender of Japan in 1945, Sumatra came under the authority of the South East Asia Command headed by British Admiral Lord Louis Mountbatten. On 17 August, Sukarno proclaimed Indonesia independence in Jakarta, and appointed Muhammad Hasan as governor of Sumatra. However, news of the proclamation was only announced by Hasan in Medan on 30 September. After allied troops landed in October, clashes with armed Republicans led to the Battle of Medan.