After Caesar 's assassination , Mark Antony had Caesar 's birth month Quintilis renamed July ( '' '' ) in his honor . After Antony 's defeat at Actium , Augustus assumed control of Rome and , finding the priests had ( owing to their inclusive counting ) been intercalating every third year instead of every fourth , suspended the addition of leap days to the calendar for one or two decades until its proper position had been restored . See Julian calendar : Leap year error . In 8 , the plebiscite '' Lex Pacuvia de Mense Augusto '' renamed Sextilis August ( '' '' ) in his honor
Caesar 's assassination
Assassination of Julius Caesar
Roman calendar