The term '40s Foes' refers to the AXIS powers during World War II. The AXIS powers were a coalition of countries led by Nazi Germany, Italy, and Japan. They were opposed by the Allied powers, which included the United States, the United Kingdom, and the Soviet Union. The AXIS powers were responsible for some of the most devastating events of the war, including the Holocaust and the bombing of Pearl Harbor. The four-letter solution to this crossword is 'AXIS, ' which is an appropriate acronym for the three countries that formed the AXIS powers.