Japan's December 1941-February 1942 invasion of Malaya and culminating conquest of Singapore is analyzed from an operational perspective. Although overshadowed by better known Pacific Theater actions in World War II, the campaign was Japan's most successful example of joint warfare and replete with lessons for the modern operational commander. Approached from the level of the commander and staff, the background and decision making processes are reviewed, with applicable areas identified for today's leaders. The need for aggressive leadership, accurate intelligence, flexible application of power, adjustment of force based on environmental conditions, and the value of logistics are the major lessons from the Japanese victory. Poor leadership and futility of trying to defend too much are among those lessons from the defeated British.