Having achieved their objective , the Epigoni returned home .
Not before they installed Thersander , son of the fallen prince Polynices ( the instigator of the first Theban expedition ) , as the city 's new ruler .
Having achieved their objective , the Epigoni returned home , but not before they installed Thersander , son of the fallen prince Polynices ( the instigator of the first Theban expedition ) , as the city 's new ruler .