Manager, Rod Stringer made 5 changes to the starting line-up following the Easter Monday defeat to Wealdstone, with Jazzi Barnum-Bobb, Mickey Spillane, Billy Knott, Tom Wraight and Scott Fenwick all returning.
The opening 5 minutes saw both sides struggle to keep a hold of the ball on a bumpy pitch, including some physical tackles, one of which saw Billy Knott receive an early yellow card for a late challenge.
Chelmsford City started to get into their groove soon after and took the lead on 16 minutes through Rhys Murphy. Following a spell of pressure, Max Porter recycled the ball back into the Chippenham box and Murphy turned well under pressure to finish past Will Puddy.
Chippenham Town scuppered a great chance to level the score on 30 minutes. Following a clearance from a Chelmsford corner, Jazzi Barnum-Bobb failed to control the ball on the near-side and was intercepted by Nick McCootie; the striker cut inside past Adrian Cascaval, but curled his effort marginally wide.
Chelmsford almost doubled their lead just before half-time on 41 minutes as Billy Knott's cross was flicked towards goal by Rhys Murphy, but the ball went millimetres past Scott Fenwick.
Chelmsford made a substitution during the interval with Lamar Reynolds replacing Tom Wraight.
With the wind starting to become stronger during the opening stages of the second half, neither side were truthfully able to create anything clear cut, but the contest remained physical with both teams giving it their all.
Word got out that Bath City had taken a two-goal lead away at Billericay Town just after the hour-mark, meaning it was crucial that the Clarets won themselves to confirm a 4th place finish.
Chippenham Town made their first substitution on 63 minutes with Jack Compton replacing Rhys Davies. Chelmsford reacted 3 minutes later by making their second sub as captain, Anthony Church replaced goalscorer, Rhys Murphy.
Will Puddy and Scott Fenwick clashed just after 72 minutes after both challenged for the ball following a Lamar Reynolds cross. No foul was given, however both players received yellow cards.
Chelmsford almost sealed the win on 73 minutes. Billy Knott fizzed a low-cross into the box towards Anthony Church who had an open goal at his disposal, but the midfielder's feet got muddled and Chippenham were able to clear their lines.
Chippenham made their second substitution on 76 minutes with Karnell Chambers replacing Nick McCootie.
City entered the final 5 minutes knowing that if the score remained 1-0, 4th place would be theirs. Rod Stringer made his final sub on 88 minute and Jonny Giles replaced Billy Knott.
Chippenham piled on the pressure in search of an equaliser and Mickey Spillane was forced into making a goal-saving block on the edge of the box to deny the hosts in stoppage time.
3 minutes were added on and Chelmsford tried to keep the ball in the corner for as long as they could to run down the click. The referee eventually blew up for full-time, confirming City's place in the Playoff Semi-Finals.
Chelmsford City will now take on Welling United away on Sunday 5th May, 3pm KO.