How was a Roman legion organized in terms of size and composition?

• A. A legion consisted of two thousand infantry and no cavalry.
• B. A legion had eight cohorts and no centurions.
• C. A legion was formed solely from allied reserves.
• D. A legion comprised roughly 4,500–5,500 infantry, organized into 10 cohorts; the first cohort was larger; each cohort divided into centuries commanded by centurions; supported by cavalry and auxiliaries.

Answer: (D)

Roman legions were large, highly organized infantry formations that operated with a clear hierarchy. A typical legion included roughly 4,500–5,500 infantry and also a cavalry component, all arranged into ten cohorts. The first cohort was larger than the others, serving as the elite core of the legion. Each cohort was made up of centuries, units of around 80 men, commanded by centurions who provided experienced leadership on the ground. The first cohort often consisted of five double-strength centuries, while the remaining nine cohorts were subdivided into six centuries each. In addition to the infantry, the legion was supported by cavalry and, crucially, by allied auxiliaries to provide additional mounts and diverse troops. This combination of a standardizable infantry backbone, a more powerful first cohort, subdivided centuries, and integrated cavalry and auxiliaries is what gives the described structure its accuracy. Other options misstate size, the presence of centurions, or the mix of forces, and don’t reflect how legions were actually organized.