The economy of the frontier: army pay, coinage and supply

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The prosperity of Augusta Raurica depended to a large extent on the Roman army. From the reign of Augustus onwards, the Rhine frontier was guarded by legions and auxiliary units stationed in camps along the river. The nearest legionary camp was Vindonissa, today's Windisch in the canton of Aargau, some forty kilometres south-east of Basel, where a legion was stationed from about 15 AD to 101 AD.¹ A legion comprised some five thousand men, to whom must be added auxiliary troops, servants, traders and families. The soldiers received regular pay in coin and spent a large part of it in the settlements around the camps and along the supply routes.

The army was, in effect, the largest economic actor of the region. It needed grain, meat, wine, oil, leather, timber, iron and a thousand other goods, paying for them with money minted by the state. The supply of the frontier armies was organised partly through requisitions and taxes in kind, partly through purchases on the market and partly through contracts with private suppliers. Merchants who specialised in army supply, the negotiatores, are attested along the Rhine by inscriptions. Some of them were organised in associations and operated over long distances, from the ports of the Mediterranean to the camps of the Rhine and the Danube.²

This pattern, in which public expenditure feeds private trade and credit, would recur many times in the history of Basel: in the pensions and subsidies that foreign powers paid to the Swiss cantons for their mercenaries, in the war loans of the seventeenth and eighteenth centuries, in the supply of the belligerent powers during the world wars and in the modern role of public procurement and pharmaceutical reimbursement. A financial centre lives on private savings and, in equal measure, on the flows of public money that pass through it.

The monetary economy of the region changed profoundly with the Roman conquest. The Celtic coinage of the Rauraci and their neighbours, a mixture of cast potin coins, silver quinarii and gold staters modelled on Greek prototypes, was replaced by the imperial currency. The Roman monetary system was based on the gold aureus, the silver denarius and a series of bronze and brass coins, the sestertius, the dupondius and the as. The coins carried the portrait of the emperor and slogans that proclaimed the virtues of his rule. Because they were legal tender throughout the Empire, their circulation from Britain to Syria created one of the largest monetary areas in history.³

Coin finds at Augusta Raurica number in the tens of thousands. They allow numismatists to follow the monetary history of the colony year by year, from the Augustan period to the late fourth century. They show periods of abundance and periods of shortage, the arrival of imitations and local copies when official supply failed, and the progressive debasement of the silver coinage in the third century, when the antoninianus, nominally a double denarius, came to contain only a few per cent of silver.⁴ The inflation of the third century, which accompanied the military and political crisis of the Empire, is one of the first well-documented episodes of monetary instability in European history. It destroyed savings, disrupted trade and led to a partial return to payments in kind.

The reforms of Diocletian and Constantine at the turn of the fourth century restored a stable gold coin, the solidus, which would remain the standard of value in the Byzantine Empire for seven centuries and give its name to the sou, the soldo and the shilling. The silver coinage never recovered its former status. The Kaiseraugst treasure, with its silver ingots stamped with official marks, belongs to this late Roman monetary world, in which precious metal by weight played a role alongside coin.

For a Swiss reader, one lesson of this monetary history is particularly familiar. A currency is only as strong as the institutions that stand behind it. The Roman currency was strong as long as the Empire was strong and weakened when the state resorted to debasement to finance its armies. Switzerland built its modern reputation on the opposite policy: a currency backed until 2000 by gold reserves under the Federal Constitution and managed by an independent central bank whose primary mandate is price stability.⁵ The chapters of Part F on the Bank for International Settlements return to the question of how central banks cooperate to preserve monetary stability.

Notes

1. On the legionary camp of Vindonissa (Windisch AG), occupied by the legio XIII Gemina, XXI Rapax and XI Claudia between c. 15 and 101 AD, see HLS, article "Vindonissa". Dates to be verified. ↩
2. On the negotiatores supplying the Rhine armies and their associations, see the epigraphic evidence collected in the literature on the Roman economy of the north-western provinces; for the region, Berger, Führer durch Augusta Raurica, 2012, chapter on trade. ↩
3. On the monetary system of the early Roman Empire and its introduction in the north-western provinces, see the standard numismatic literature; for coin finds at Augusta Raurica, the publications of the Museum Augusta Raurica (Inventar der Fundmünzen der Schweiz). ↩
4. On the coin finds of Augusta Raurica and the debasement of the third century, see the publications of the Inventar der Fundmünzen der Schweiz and the Museum Augusta Raurica. Figures to be verified. ↩
5. The gold backing of the Swiss franc was abolished with the revision of the Federal Constitution in force since 1 January 2000 (Art. 99 Cst.) and the National Bank Act of 3 October 2003 (SR 951.11), in force since 1 May 2004; the price stability mandate is set out in Art. 5 para. 1 NBA. ↩

For general information only. This article does not constitute legal or tax advice, does not replace advice on an individual case and creates no lawyer-client relationship. It reflects the legal position as of September 2025.