Military conquest by the Republic followed extensive trade with the provinces, and was often predicated on protection of valuable transit routes and Rome’s traveling merchants. Trade between the provinces and Rome was substantial, by land and by sea, and was very profitable. Trade goods consisted primarily of agricultural products, including grain, wine, spices, fruits and nuts, etc. In addition, both common and precious metals, textiles, manufactured goods, agricultural implements, weapons, pottery, etc. were significant. Financing for these ventures was generally through intra-family sources of the Patrician and Equestrian classes; detailed historical books and records show these enterprises were substantial and well-organized. Rome’s control of the terms of trade with its provinces was extensive, sophisticated and benefited from protection by its military; the provincial trading system produced great and sustained wealth for Rome for generations.
Conquered provinces were ruled by appointed Roman military governors, backed by garrisoned Roman troops, and held absolute authority over the populace, commerce and taxes. Governors were expected to generate wealth for themselves and to pay their armies; military officers shared in confiscated wealth. Provinces were required to contribute men, money and material to Rome’s military. Equestrians running private companies administered profitable contracts in the provinces for tax collection, military supplies, and sale of plunder and slaves.
Profits from military supply and tax administration contracts benefited the Equestrian class and their investors. Expropriated property was hauled back to Rome by military commanders and sold at auction. Provincial residents and opposing tribal armies were brought back and sold as slaves. Merchants of the Equestrian class benefited from sale of Roman goods to the provinces, as well as sale of provincial goods to Rome and other provinces. So provincial conquests, by expropriation of property, and control of commerce, brought great wealth to Rome.
The Republic had designed stable, representative government; had accomplished great military conquest; and achieved great wealth through its domination of trade in the known world.