The regime of the Nine Governors and Defenders of the Commune and People of Siena: a merchant oligarchy that excluded the magnate nobility, rotated a nine-member executive every two months, balanced councils and a foreign podestà, translated its statutes into the vernacular and commissioned Lorenzetti's frescoes of good and bad government.
Siena was one of the great commercial and banking cities of thirteenth-century Tuscany and a Ghibelline rival of Florence. After the Guelf turn of the 1260s–1280s, a series of short-lived governments of "the people" alternated with the power of the magnate families (casati). In 1287 the city entrusted executive power to a college of Nine Governors and Defenders of the Commune and People of Siena. William Bowsky's study of the regime, based on the city's exceptionally rich archives, describes nearly seventy years of relative stability, public building and administrative development.
The Nine presided over a building programme that still defines Siena: the Palazzo Pubblico (begun in the 1290s) and its tower, the paving of the shell-shaped Campo, fountains fed by underground aqueducts (bottini), city walls, roads and the planned enlargement of the cathedral. They regulated markets, the wool industry and building heights and façades on the Campo. The collapse of the great Bonsignori banking house in 1298 had already weakened Sienese finance. In 1338–1339 Ambrogio Lorenzetti painted the frescoes of good and bad government in the Nine's council room. Nicolai Rubinstein read them as illustrating Aristotelian and Thomist ideas of the common good; Quentin Skinner argued that they draw on pre-humanist Ciceronian rhetoric of civic virtue and justice. Either way they are a rare statement of a regime's own political ideals.
The Nine faced repeated conspiracies and revolts by excluded groups: magnates, judges and notaries, and workers. The most serious, in 1318, involved butchers, notaries and magnates. The regime relied on the podestà's courts, on militias, and on co-opting magnates into office outside the Nine. Siena also fought territorial wars in southern Tuscany and was drawn into conflicts between Florence, the papacy and imperial claimants.
The Black Death of 1348 killed a large part of the population and halted the cathedral enlargement. In March 1355, when Emperor Charles IV entered the city, magnates and popular groups rose against the Nine and overthrew them. They were succeeded by the Twelve (1355–1368) and further unstable regimes until the Medici-led conquest of 1555. The regime is remembered as Siena's era of "good government", though it was a narrow oligarchy.
Nearly seventy years of comparatively stable government by a rotating nine-member executive drawn from merchant families, with a foreign podestà, large councils, detailed fiscal administration and a vernacular constitution. The regime built much of medieval Siena's civic fabric and commissioned the frescoes of good and bad government.
The regime excluded magnates, judges, notaries and artisans, who conspired against it repeatedly. Financial strain and the Black Death of 1348 weakened it, and when Emperor Charles IV entered Siena in March 1355 a coalition of magnates and popular groups overthrew the Nine. A sequence of less stable regimes followed.
From 1287 to 1355 Siena was governed by a college of Nine serving two-month terms, drawn from merchant families and excluding members of magnate houses, alongside a foreign podestà and a large General Council.[1][2][3]
Lorenzetti's frescoes of good and bad government in the Palazzo Pubblico express an Aristotelian and Thomist conception of the common good.[1][2]
In 1309–1310 the Sienese commune had its constitution (the Costituto) translated into the vernacular.[1][2]