On the battlefield, cohorts assumed a formation about five hundred feet wide by fifty feet deep. In another departure from the manipular formation, the cohort formed a continuous front while engaged in hand to hand fighting. In action, the lines of the cohort rotated, allowing a fresh line to appear at regular intervals of about 10 minutes. The engaged line withdrew and fell to rear until its turn came again. No other opponent operated in this fashion, hence an attacking force was continuously faced with relatively fresh troops during the entire battle. Eventually the enemy could no longer stand the strain and would succumb to exhaustion. If they broke, the hasty disorganized retreat usually turned into a fatal rout.
The first real test of the Marian tactical system came at Aix-En- Provence when a combined army of Ambrones and Teutones, numbering around 130,000 warriors confronted Marius consular army of six legions. The battle was one-sided and resulted in the extermination of both tribes -- Marius took 17,000 warriors prisoner and another 130,000 dependents. The following year, at Vercellae in the Po valley, Marius defeated the Cimbri, killing 140,000 and enslaving 60,000 warriors, and taking a like number of women and children prisoners. The German threat was removed. Marius was elected consul for the 6th time, and hailed the "Third Founder of Rome." The Marian tactical system became the model for the rest of Rome's history.