In 1840, Takashima was made a "toshiyori", or Senior Administrator, for the city of Nagasaki. From 1840, following the outbreak of the Opium War in China, Takashima appealed to the Shogunate to reinforce Japan's military capabilities. The war in China had made clear that traditional ways were not sufficient to keep the Westerners at bay, and that radical modernization, especially that of artillery, was needed to be able to resist.