Complex sentence: Subsequently, Schreiber became intimately involved in the construction of the CPR; in June of 1880 he replaced a retiring Fleming as the chief engineer for the project, and by July of that same year had become general manager of all government railways in operation.
Split into simpler sentences: Subsequently, Schreiber became intimately involved in the construction of the CPR. In June of 1880 he replaced the retiring Fleming as the chief engineer for the project and by July of that same year had become general manager of all government railways in operation.