Cohorts, Cavalry and Whatever Goes

[Sean Manning]

The numbers for Caesar’s army tell an interesting story. Caesar has stripped the ninth legion down to a 50% capacity. I cannot believe the ninth lost this many men at Dyrrachium, some yes but not 50%. So my hypothesis is Caesar stripped it down to 50% and distributed the remainder among the other seven legions.

For what its worth, my forthcoming master's thesis ("Service and Supply in the Achaemenid Persian Army," University of Calgary) suggests based on comparative evidence that losses to desertion, disease, accidents, and combat on the order of 1% per month would have been perfectly normal. Lack of pay, lack of food, intense and unsuccessful combat, could all increase that dramatically, and all of those conditions apply to Caesar's war against the republic. Many of Caesar's legions had been on campaign for years with few or no reinforcements. In addition, a significant fraction of an army would be unable to fight on a given day due to sickness, wounds, garrison duty, etc. One would have to run the numbers on that war, but I don't find the idea that Caesar's legions were down to 3,000 effective combatants each on the day of Pharsalus hard to believe, and in any case he had access to the records.