Complex sentence: After a full year in France, he returned to England and was briefly posted as Senior Medical Officer for the Billeting Area before being appointed Assistant Director of Medical Services to organize the medical support for the newly formed 3rd Canadian Division.
Split into simpler sentences: After a full year in France, he returned to England, where he was briefly posted as Senior Medical Officer for the Billeting Area. He was then made Assistant Director of Medical Services with the duty of organizing medical support for the newly formed 3rd Canadian Division.