The game, like last week's, was a scrappy affair at times, but the town had learnt from the previous encounter and spread the ball wide on more occasions, and not allowing a very physical Chepstow team to stop them playing.
Even though Monmouth had all the play and plenty of chances, they only went into the break one-nil up, after Luke Cleaves slotted Alex Hunt's free kick into the corner.
The second half was a massive improvement, with goals from the ever improving George Riley, a second from Cleaves, and a cracking free kick from Hunt.
Jordan Boxhall-James completed the rout when he slid in at the back post to convert a Cleaves cross.
Manager Nick Oxford was very pleased with his team's performance: apart from the goal-scorers, there were good displays from Alex Bradley at left back and Tom Burns at centre half. George Badman also had one of his best games.