The “unidentified” person in the back row of the group picture of the Project Matterhorn B team (PHYSICS TODAY, April 2009, page 32) is the late A. Carl Haussmann, then a captain in the US Army (and former all-American lacrosse player from West Point) and later a long-time associate director and, briefly, acting director of Lawrence Livermore National Laboratory. Carl was a leader in the development of weapons and laser programs at Livermore and a key reason for their success. He always remembered John Wheeler with affection and respect, and he looked on his time working on Project Matterhorn as a major formative experience.