Campaign history of the Roman military

From its origin as a city-state on the peninsula of Italy in the 8th century BC, to its rise as an empire covering much of Southern Europe, Western Europe, the Near East, and North Africa to its fall in the 5th century AD, the political history of Ancient Rome was closely entwined with its military history. The core of the campaign history of the Roman military is an aggregate of different accounts of the Roman military's land battles, from its initial defense against and subsequent conquest of the city's hilltop neighbors on the Italian Peninsula, to the ultimate struggle of the Western Roman Empire for its existence against invading Huns, Vandals and Germanic tribes. These accounts were written by various authors throughout and after the history of the Empire. Following the First Punic War, naval battles were less significant than land battles to the military history of Rome due to its encompassment of lands of the periphery and its unchallenged dominance of the Mediterranean Sea.

The Roman army battled first against its tribal neighbours and Etruscan towns within Italy, and later came to dominate the Mediterranean and at its height the provinces of Britannia and Asia Minor. As with most ancient civilizations, Rome's military served the triple purpose of securing its borders, exploiting peripheral areas through measures such as imposing tribute on conquered peoples, and maintaining internal order. From the outset, Rome's military typified this pattern, and the majority of Rome's campaigns were characterised by one of two types. The first is the territorial expansionist campaign, normally begun as a counter-offensive, in which each victory brought subjugation of large areas of territory and allowed Rome to grow from a small town to a population of 55 million in the early empire when expansion was halted. The second is the civil war, which plagued Rome from its foundation to its eventual demise.

Despite their formidable reputation and host of victories, Roman armies were not invincible. Romans "produced their share of incompetents" who led Roman armies into catastrophic defeats. Nevertheless, it was generally the fate of even the greatest of Rome's enemies, such as Pyrrhus and Hannibal, to win the battle but lose the war. The history of Rome's campaigning is, if nothing else, a history of obstinate persistence overcoming appalling losses.

Knowledge of Roman history stands apart from other civilizations in the ancient world. Its chronicles, military and otherwise, document the city's very foundation to its eventual demise. Although some histories have been lost, such as Trajan's account of the Dacian Wars, and others, such as Rome's earliest histories, are at least semi-apocryphal, the extant histories of Rome's military history are extensive.

Rome's earliest history, from the time of its founding as a small tribal village, to the downfall of its kings, is the least well preserved. Although the early Romans were literate to some degree, this void may be due to the lack of will to record their history at that time, or such histories as they did record were lost.

Although the Roman historian Livy (59 BC – 17 AD) lists a series of seven kings of early Rome in his work Ab urbe condita, from its establishment through its earliest years, the first four kings (Romulus, Numa, Tullus Hostilius and Ancus Marcius) may be apocryphal. A number of points of view have been proposed. Grant and others argue that prior to the establishment of the Etruscan kingdom of Rome under the traditional fifth king, Tarquinius Priscus, Rome would have been led by a religious leader of some sort. Very little is known of Rome's military history from this era, and what history has come down to us is more legendary than factual. Traditionally, Romulus fortified the Palatine Hill after founding the city, and shortly thereafter Rome was "equal to any of the surrounding cities in her prowess in war".

The first of the campaigns fought by the Romans in this legendary account are the wars with various Latin cities and the Sabines. According to Livy, the Latin village of Caenina responded to the event of the abduction of the Sabine women by invading Roman territory, but were routed and their village captured. The Latins of Antemnae and those of Crustumerium were defeated next in a similar fashion. The remaining main body of the Sabines attacked Rome and briefly captured the citadel, but were then convinced to conclude a treaty with the Romans under which the Sabines became Roman citizens.

There was a further war in the 8th century BC against Fidenae and Veii. In the 7th century BC there was a war with Alba Longa, a second war with Fidenae and Veii and a second Sabine War. Ancus Marcius led Rome to victory against the Latins and, according to the Fasti Triumphales, over the Veientes and Sabines also.