How did the actions of gaius marius change the roman republic

Gaius marius was noted for his important reforms of Roman armies, authorizing recruitment of landless citizens, eliminating the manipular military formations, and reorganizing the structure of the legions into separate cohorts. Marius defeated the invading Germanic tribes (the Teutones, Ambrones, and the Cimbri), for which he was called "the third founder of Rome." His life and career were significant in Rome's transformation from Republic to Empire.