In the tumultuous period following Caesar's death, during the ascendancy of the Second Triumvirate, Gaul was acted upon by various commanders, until M. Vipsanius Agrippa arrived as proconsul in 39 to quell unrest. Scholars have paid relatively scant attention to the question of why Gaul failed to take advantage of Rome's disarray during the civil wars of the 40s and 30s to revolt "in toto"; it is sometimes assumed that the population was too decimated to take a stand, but the numbers in so far as they are known make this unlikely. In 57, for instance, Caesar had reported that the Nervii had 50,000 men of fighting age; he supposed that only 500 survived the Battle of the Sabis, but five years later they were able to provide a force of 5,000 men. Although the figures may be unreliable in the absolute, they indicate the resilience of the population. In 52, after the surrender of the pan-Gallic army at Alesia, Caesar had granted amnesty to the armies of both the Arverni and Aedui, each of which he estimated at 30,000 men, and sent them home. After the failure of Vercingetorix's strategy of massing allied forces, the surviving Gallic leaders had continued to wage a guerrilla war with some success and hope of attrition, until Marcus Antonius (Mark Antony) came to an arrangement with the last Celtic king known to retain his independence, Commius of the Atrebates, who had led the relief forces at Alesia. Over the course of the following two decades, Gallic losses in the 50s would have been replaced by the maturation of the male population, while available Roman forces were largely occupied by fighting each other. The Gauls may have imagined that the Romans would weaken themselves in civil war to such an extent that a rebellion was moot or not worth the trouble; Caesar reports that the Gauls kept themselves informed about political events in Rome that might affect them.