The empire reaches its greatest territorial extent
At Trajan's death the empire nominally includes Dacia, Armenia, Assyria and Mesopotamia. His successor Hadrian abandons the eastern conquests almost immediately. The retreat is the informative part: the limit of the empire was not the limit of its armies but the limit of what could be supplied, garrisoned and administered at the speed information travelled.
Historical — it happened, and the record is settled.
Subjects
- Trajan (Marcus Ulpius Traianus) · person · Rome, Dacia, Mesopotamia; born in Hispania Baetica · not located
- The Roman Road Network · network · Mediterranean-wide, from Britain to Mesopotamia · not located
- The Roman Legion · military_formation · Frontier provinces, principally Rhine, Danube, Britain, Syria, North Africa · not located
- Hadrian's Wall · site · United Kingdom
Evidence
Partly verified — Core facts are sourced; some optional detail is deliberately absent. This is the standing of the weakest source, not an average.
Digital reconstruction of the Roman road network (DARMC and successor mapping projects)
Network models place total Roman road length between roughly 80,000 km (major viae only) and c. 192,861 km across c. 7,154 modelled segments at the empire's peak, depending on inclusion criteria. A 2025 mapping effort reported that the exact course of only about 2.7% of the network is known with certainty.
Digital Atlas of Roman and Medieval Civilizations, Harvard University; reported in la Brújula Verde · DARMC ongoing; mapping report November 2025 · Partly verified
Digital Atlas of Roman and Medieval Civilizations, Harvard University, https://darmc.harvard.edu/ ; 2025 mapping report at https://www.labrujulaverde.com/en/2025/11/the-most-detailed-map-of-the-roman-empires-road-network-reveals-that-we-know-with-certainty-the-location-of-only-27-of-its-roads/
Size and structure of the imperial Roman army (synthesis of unit-list reconstructions)
An imperial legion had a nominal strength of c. 5,000-6,000 men in ten cohorts, with roughly equal auxiliary numbers alongside. Total army strength is reconstructed as c. 250,000 under Augustus rising to a peak of roughly 450,000 by 211 CE in c. 33 legions and c. 400 auxiliary units. All totals are modern reconstructions from unit lists, not from any surviving muster roll.
Wikipedia synthesis of Holder, Duncan-Jones, Le Bohec and MacMullen unit-strength studies · accessed 2026 · Partly verified
Overview and citations at https://en.wikipedia.org/wiki/Size_of_the_Roman_army and https://en.wikipedia.org/wiki/Imperial_Roman_army ; underlying figures from A. K. Goldsworthy and R. Duncan-Jones
Recorded on Trajan (Marcus Ulpius Traianus)
- Construction of the Via Appia begins
- The Punic Wars
- The Augustan settlement: Octavian becomes Augustus
- Caesar crosses the Rubicon
- The empire reaches its greatest territorial extent
- Construction of Hadrian's Wall begins
- The Antonine Constitution (Constitutio Antoniniana)
- Alaric's Goths sack Rome
- Odoacer deposes Romulus Augustulus - the contested 'fall' of the Western Roman Empire
- Digital mapping shows most of the Roman road network is unlocated
Related
Related because they share a subject in the Atlas — never because the text looks similar.
- Digital mapping shows most of the Roman road network is unlocated · 2025
- Odoacer deposes Romulus Augustulus - the contested 'fall' of the Western Roman Empire · 0476-09-04
- Alaric's Goths sack Rome · 0410-08-24
- The Antonine Constitution (Constitutio Antoniniana) · 0212
- Construction of Hadrian's Wall begins · 0122
- Caesar crosses the Rubicon · -0049-01-10
- The Augustan settlement: Octavian becomes Augustus · -0027
- The Punic Wars · 264-146 BCE