Iberian expansion over the oceans: law and politics of mare clausum on the threshold of Modernity (XV-XVI centuries)

Oceangoing navigation played a major role in the development of the law of the sea during the Early Modernity. The vastness of the oceans precluded straightforward solutions and stretched to their limit pre-existing ideas concerning the legal status of the sea. In the beginning, the tense political rivalry between Portugal and Castile dominated legal discourses concerning the oceans, with the Holy See playing a cumbersome role. At the end of the fifteenth century, the Iberian countries found a compromise and coordinated their endeavours. Throughout the sixteenth century, they sought to exclude other Europeans from sailing to the Indies. Hence, this contribution shall investigate Iberian claims over the oceans, which largely provided the premises to Grotius’ Mare Liberum (1609) and to the scholarly diatribe between the supporters of the principles mare liberum and mare clausum.