Cinderford started the stronger and twice went desperately close to scoring in the opening stages but could not ground the ball.
Monmouth then settled and quickly grew into the game, scoring an unconverted try in the corner followed minutes later by a run in under the posts from a quickly taken tap penalty, which saw the visitors open up a 0-12 lead.
Cinderford rallied, driving over through Riley Preece for their first try to make it 5-12.
Another quickly taken tap penalty saw Monmouth go over in the corner to make it 5-17 to the visitors.
Cinderford responded well, taking the game to their visitors with an excellent multi- phased passage of play that ultimately saw Harry Hemms crossing the line to narrow the deficit to 12-17.
Cinderford finished in the ascendency.
As the match drew to a tantalising close, Cinderford secured their own penalty line-out ball, setting the platform for the forwards to drive over from close range for what seemed a certain scoreboard-levelling try.
However, the grounding was not seen by the officials and so a try could not be awarded.
Pictures courtesy of Kairos Sports Photography.