Simplify the following text for a Grade 13 native English-speaking person.
Original: Before the course was finished , he was transferred to the instructing staff and in June 1943 he was appointed the first commandant of the new Police Civil Affairs Training Centre at Peel House in London ( gazetted with the rank of Lieutenant-Colonel ) and charged with the task of setting up the training school for policemen and provost officers who would maintain law and order in Axis territory as it was liberated by advancing Allied forces .
Simplified: Before the course was finished , he was transferred to the instructing staff and in June 1943 he was appointed the first commandant of the new Police Civil Affairs Training Centre at Peel House in London ( with a rank as if he was a Lieutenant-Colonel in the army ) . He had to set up the training school for policemen and provost officers ( military police ) who would keep law and order in Axis territory as it was liberated by advancing Allied forces .