The four southern European countries had an extensive agricultural sector. Their rate of industrialization lagged behind western Europe's although Italy, and to a lesser degree Spain, had, from 1880 to 1910, formed a significant industrial sector. Their political institutions were fragile, tarnished from political polarization and instability in the transition to mass politics in the 1910s and 1920s. In the case of Greece, Portugal and Spain, monarchies were not particularly stable during the nineteenth century. Their common feature was the Crown's varying ability to manipulate the electoral procedure and parliaments through the distribution of spoils in the context of a patronage system. This system tended to ensure political control in the periphery through the intermediation of local bosses. In Italy the political system of the constitutional monarchy had worked rather smoothly after the unification of the country in 1861. ‘Transformismo’, the ability of the monarchy and its various partners to produce pliable majorities in parliament, would be tested in the early twentieth century. The army was a factor occasionally intervening in politics. It served often as the catalyst for the gradual opening of the political system to rising middle-class groups but increasingly during the twentieth century was mainly a conservative force apprehensive of the destabilizing influence of militant labour and Socialism.

Southern Europe Entering the Era of Mass Politics

World War I strained every country in distinct ways but in general it was a test for its institutions and its ability to integrate various social forces and interests.