Frank was employed in the wholesale hardware house of Moore and Thomas, and his prospects for the future were very bright when the United States entered the World War. Frank was above everything else a hundred-per-cent American, and if he had consulted only his own wishes would have enlisted at once. But his mother's dependence upon him made him hesitate. An episode occurred, however, that decided him, when he was forced to knock down a burly German who had insulted the American flag. There was no further opposition by his mother, and he joined the Thirty-seventh Regiment, a Camport regiment with a glorious record in the Civil War, and one which had recently seen service on the Mexican border. Billy Waldon, a close friend of Frank, was already a member, and Bart Raymond, Frank's special chum and a fellow employee, joined also. Another friend, Tom Bradford, tried to join, but was rejected on account of his teeth. He was afterward accepted in the draft, however, so that the four chums, to their great joy, found themselves together in the same regiment. There was one man in the Moore and Thomas firm who was a bitter and malignant anti-American from the start. His name was Nick Rabig, and he was foreman of one of the departments. He was born in America, but his parents were German. Rabig and Frank Sheldon were at sword's points most of the time because of the former's bullying disposition, and after Rabig had been caught in the draft and forced into the ranks of the old Thirty-seventh he got from Frank the thorough thrashing which had been for a long time coming to him. What experiences the Army Boys went through in the training camps, how narrowly they escaped a submarine attack on the way to Europe, what exciting adventures they met with on their first contact with the enemy, are described in the first volume of the series entitled: "Army Boys in France; Or, From Training Camp to Trenches." After they had once reached the scene of action the adventures of the Army Boys multiplied rapidly. Trench warfare was soon outgrown, and open fighting in the field became the order of the day. At one time when the American troops were advancing, the boys became separated from their comrades and were compelled to leap from a broken bridge into a stream, and when they attempted to swim to the other side found themselves in the enemy's hands. For a time a German prison camp with all its horrors loomed up before them, but from this they were saved by a friend of theirs, Dick Lever, who swooped down in his airplane, scattered the enemy guards, and carried his friends back in safety to their own lines. Frank had the good luck to hear encouraging news about his mother's property from a French colonel whose life he had saved under a rain of fire when the officer, Colonel Pavet, was lying wounded on the battlefield.