Complex sentence: After the Vichy government was created, Touvier and his family were firm supporters of Maréchal Petain and both father and son joined the Vichy veterans' group when it was founded in 1941.
Split into simpler sentences: After the Vichy government was created, Touvier and his family were firm supporters of Maréchal Petain. They both joined the Vichy veterans' group when it was founded in 1941.