The ex-Crewe academy star, signed from the Railwaymen earlier this summer, will now aim to get some first team experience and help push his way towards a place in the Potters first team in the future.
Marshall, 18, has impressed as a substitute in friendlies against Newcastle Town and Nottingham Forest whilst he also scored a hat trick in a youthful reserve sides 4-0 win away at Mangotsfield, so far the only success for the Potters this pre-season.
Marshall and fellow Crewe graduate Matthew Lund turned down deals at the Alexandra Stadium before contacting City's academy director Steve Holland, the man who helped bring them through the ranks at Gresty Road, and the pair then agreed terms to become the Potters first summer signings.