 Complete the following phrase:  In retirement C. H. Ellis wrote a book about the Malleson mission: The Transcaspian Episode. Among the incidents addressed in the book was the execution of 26 Commissars  including Stepan Shahumyan  of a Soviet client, the Centrocaspian Dictatorship, in September 1918. The commissars had earlier fled the Mussavatist Azerbaijan advanced guard in the September Days of 1918 just before the Turks 