The Pallazzo Publicco in Siena
Restoration of the republic after 1404 enabled the Priors towards an extensive embellishment of the Pallazzo Publico. (...) Among the first of the commissions for the building was the redecoration of the chapel holding a Maesta from 1302 by Duccio and located next to the room in which Simone Martini had painted his Maesta.
In 1406-07 Taddeo di Bartolo (1362/63 Siena-1422 Siena), perhaps a student of Bartolo di Fredi (see Fig. 5.17), decorated its walls with frescoes and scenes from the life of the Virgin, the city's patron saint. (...) In 1413-14 the Priors again turned to Taddeo di Bartolo to paint a cycle of paintings for the antechapel of the Palazzo Publico, a space that functioned as an important passage between other rooms of the palace. On one wall, shown in the picture benearth, Taddeo painted allegories of Justice and Magnanimity under the two arches. Beneath each he placed a figure from Roman history exemplifying the concept. Below Justice (at left) there are Cicero, M. Porcius Cato, and P. Scipio Nasica; below Magnanimity (at right) Curius Dentatus, Furius Camillus, and Scipio Africanus. Each group of Roman heroes is labeled with an inscription in Latin, and each figure bears a further Latin Inscription below his feet. The inscriptions between M. Curius Dentatus and F. Furius Camillus claim them as founders of Siena, while others under Cicero and Cato speak of their fight for liberty and justice.
In the same room (anticappella) must be somewhere (I don't find a room description) these 2 figures (Caesar and Pompey):
The whole looks like a relative to the 9-worthies concept (in a hidden form). The picture is described to present the virtues of the republic, perhaps that's the reason, why the 9th figure is missing (a reigning hero), and Caesar and Pompey (hostile to the republican idea) are placed at a different location (just my humble own idea, maybe a stupid idea).
About the Palazzo Pubblico in Siena
https://it.wikipedia.org/wiki/Palazzo_Pubblico_(Siena)