I'm quite interested in the removal of the Hastati, Principes and Triarii elements introduced by the Marian reforms in 107 BC, and how it affected the Roman army at first.

Looking on Wikipedia for Roman battles just after the reform brings two Roman defeats in the Cimbrian War: the Battle of Burdigala (107 BC) and the disastrous Battle of Arausio (105 BC).

Both articles mention other causes for defeat, but I'm wondering if inexperience in a new system on the battlefield played a part.

Of course, in case the new Marian legions didn't made their debut in neither of those battles, where was it and what impact had the new composition of the army?

  • 3
    According to the linked article for the Battle of Arausio, this disaster was a major impetus for Marius' reforms, so I assume the legions involved were formed under the old scheme. My guess is that the first legions recruited according his reforms would been one he raised himself, so the first battles would have also been led by him. That would be mean the earliest battles would've been during his campaign at the end of Jugurthine War or maybe his campaigns late in the Cimbrian War (eg. the Battle of Aquae Sextiae).
    – Ross Ridge
    Sep 21, 2016 at 21:43

1 Answer 1


Firstly, this is an excellent question.

Marius created the reforms during his time as proconsul after Rome's struggles in the first half of the Cimbrian wars against the Northern Rhone-located Cimbri and Teutons tribes. The absolute destruction at Arausio was part of the reason for the reform's institution. It is unlikely that any battle led before Arausio including Arausio used the reforms- many sources including the Wikipedian articles upon the Cimbrian war state the Roman forces in terms of strict numbers and tend to only use the term "legions" and "cohorts" after and in the battle of Aquae Sextiae.

For this reason, I think we can deduce the first use of the legions was at Aquae Sextiae.

Marius eliminated the manipular system and invented the term "cohort". Another reason I think we can state with solidarity that Aquae Sextiae was the first usage is because of Marius's reform that allowed non aristocratic plebeians to join the army. This would only have been done due to the absolute deficit of Roman soldiers, which would have occurred after the loss of 80,000 at Arausio.

The system eliminated many of the conventions of the Republican army and ensured that a fully staffed and annually paid Roman army was always at hand. I found this to be an excellent source detailing many of the impacts of the war and the changes in the Army post triplex acies.

I hope this helped and gave a better idea on the reforms and approximate time of the institution of the reforms.

  • +1, I think, too, it was at Aquae Sextiae, which Plutarch marks it as the introduction of the Marian pilum. Last link is really nice :)
    – Brasidas
    Sep 26, 2016 at 3:26
  • Good answer, however I must point out a small technical detail. Marius' reforms allowed for a group of unpropertied plebeians known as the "capite censi" or "head count" to enlist for military service. All plebeians were non aristocratic as the aristocratic class known as the "patricians" were those who could claim descent from the original advisory body of the Kings of Rome. Oct 24, 2016 at 17:15

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