One in the heart and one in the head

" "In March 2003, a Marine captain stood in front his company, showing images of the wide range of uniforms and garb the enemy might wear. After each image, he would ask for the correct response, and the answers were so consistent that halfway through the lecture, Marines began shouting in chorus, "One in the heart, one in the head," as each new image appeared. The message was clear: Identifying the enemy won't be easy, so be prepared to kill a wide range of people.""