When the allied front collapsed, sixteen year old Charles, on the strength of boy scout badge in first aid, volunteered to help at a British field hospital, during the Evacuation of Dunkirk.
[2] He started studying at the City College of New York, but left to enlist in the United States Army.
He was assigned to the Army military intelligence due to his ability to speak French, Dutch, and German.
[2] According to a profile of Poser by the FRCPE, he credited his two mentors, Merritt and Bogaert, with inspiring the research that made him famous.
His major scientific accomplishment was "the first definitive system for measuring and describing MS", the Poser criteria unveiled in 1983.