Peace among Democratic and Oligarchic Republics

A list was compiled of virtually all significant military confrontations between republics throughout history. By including regimes only marginally republican, some forty cases were found from ancient Greece to the 1990s; about half of these had significant combat. Detailed historical investigation of each case reveals consistent patterns. A striking lack of wars between well-established democracies prevailed not only among modern states but also among earlier regimes commonly described as democracies, for example in medieval Switzerland. A historically more numerous class of republic is the oligarchies, where those in power hold equal rights but deny such rights to other important groups (e.g. South Africa). Remarkably, oligarchies scarcely ever made war on other regimes of their own type. Oligarchies did commonly fight democracies. It also appears that both types of republic, unlike all other regimes, have tended to form durable peaceful leagues among themselves. These reliable and general observations are not consistent with explanations solely in terms of institutional structures, but they can be understood in terms of domestic political culture. Leaders who negotiated with fellow citizens as equals invariably treated foreign leaders in the same non-violent manner, provided that they perceived the foreigners too as political equals.