While at Fort Bliss, they trained military, industrial, and university personnel in the intricacies of rockets and guided missiles. As part of the Hermes project, they helped refurbish, assemble, and launch a number of V-2s that had been shipped from Germany to the White Sands Proving Ground in New Mexico. They also continued to study the future potential of rockets for military and research applications. Since they were not permitted to leave Fort Bliss without military escort, von Braun and his colleagues began to refer to themselves only half-jokingly as "PoPs" – "Prisoners of Peace".