Exercise Grand Slam was an early major naval exercise of the newly formed North Atlantic Treaty Organization (NATO). This 1952 combined naval exercise took place in the Mediterranean Sea, and it included a naval force that was described as being "the largest armada to be assembled in that area since the end of World War II." Exercise Grand Slam was an early test for NATO's Allied Forces Southern Europe. With Exercise Longstep, this exercise served as the prototype for future NATO maritime exercises in the Mediterranean Sea during the Cold War.