Hideki Tojo was the Prime Minister of Japan during World War II. He played a key role in Japan's military expansionism and decision to attack Pearl Harbor in 1941, leading Japan into full-scale war with the Allied powers. Tojo's leadership oversaw Japan's involvement in numerous military campaigns across Asia and the Pacific. He was known for his authoritarian style and ruthless approach to governance, which included suppressing dissent and enforcing strict control over Japan's military and civilian sectors.