Composite monarchy

A composite monarchy (or composite state) is a historical category, introduced by H. G. Koenigsberger in 1975 and popularised by J. H. Elliott, that describes early modern states consisting of several countries under one ruler, who governs his territories as if they were separate kingdoms, in accordance with local traditions and legal structures. The composite state was the typical kind in the early modern period. Koenigsberger divides composite states into two classes: those, like the Spanish Empire, that consisted of countries separated by either other states or by the sea, and those, like Poland–Lithuania, that were contiguous.

Theorists of the 16th century believed that "conformity" (similarity in language and customs) was important to success of a composite state. Francesco Guicciardini praised the acquisition of the Kingdom of Navarre by the King of Aragon in 1512 on account of their conformità. Yet, differences could be persistent. Navarre retained its own law and customs separate from the rest of Spain down to 1841. In France, a far more unified state than Spain in the early modern period, the state was divided into different customary tax regimes, the pays d'élection and pays d'état. This was abolished during the 1789 Revolution.

The 17th-century Spanish jurist Juan de Solórzano Pereira identified the composite state as one whose components were aeque principaliter (equally important), as opposed to an "accessory" union, in which a newly acquired territory was subsumed under the laws of an already existing one, such as when New Spain was incorporated into the Crown of Castile, or when Wales was joined to England.

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