John Hopson has always known his service during World War II helped in the defense of America’s freedom. But it was not until recently he discovered his service was also part of one of the major turning points in human history.

Hopson, who served in the U.S. Army, said at one point while he was traveling on a troop ship in the Pacific, several mysterious passengers were brought on board. None of the crew was allowed to associate with the unknown individuals. The strange men were eventually dropped off and the rest of the crew traveled on to begin their preparation for the invasion of Japan.