The emergence of "early-modern" history as a distinct and unified field of study covering the period from around 1500 to around 1800 owes much to the Cambridge Studies in Early Modern History series that Helmut Koenigsberger, who has died aged 95, established in 1966 with JH Elliott. Until the 1970s, early-modern European states were referred to as "nations", but there was a crucial difference between most of them and modern nation-states. Helli, as Koenigsberger was widely known, brought this out by coining the term "composite monarchies". Whether in England, France, Spain, the Holy Roman empire, the Polish-Lithuanian Commonwealth or the Ottoman empire, one ruler governed different territories as if they were separate kingdoms.
The dominant strand of Helli's mature research concerned parliamentary institutions and republicanism. Early essays were assembled in Estates and Revolutions (1971), but it was his article Monarchies and Parliaments in Early Modern Europe (1978) that prompted enduring debate over the nature of the early-modern state.