Debating the Free Sea in London, Paris, The Hague and Venice: The Publication of John Selden’s Mare Clausum (1635) and Its Diplomatic Repercussions in Western Europe

Martine Julia Van Ittersum (Lead / Corresponding author)

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Politics, religion and legal argumentation were inextricably intertwined in the reception of John Selden’s Mare Clausum/The Closed Sea (1635). The work’s writing and printing history is closely tied to Stuart foreign policy, particularly James I’s and Charles I’s attempts to tax the Dutch herring fisheries. Mare Clausum’s immediate impact on European international relations has received little attention from historians so far. It is clear, however, that government authorities in London, The Hague and Venice expected an official reply from Hugo Grotius, author of Mare Liberum/The Free Sea (1609) and Swedish ambassador in Paris. Yet the latter declined to assist the Dutch authorities in this matter, blaming them for his imprisonment in 1618-1621 and his second banishment from Holland in 1632. The antipathy was mutual. The Dutch authorities abhorred Grotius’ pleas for religious tolerance and commissioned his Calvinist kinsman Dirk Graswinckel to respond to Selden instead. Graswinckel had already published Libertas Veneta/Venetian Liberty (1634), a learned defense of the Republic of Venice’s political interests. In ‘Vindiciae maris liberi’/Vindication of the Free Sea (written 1636-1637), he tried – but arguably failed—to reconcile Dutch claims to freedom of navigation, trade and fishing with Venetian claims to the Adriatic. It never appeared in print.
Original languageEnglish
Number of pages18
JournalHistory of European Ideas
Early online date18 Jan 2021
Publication statusE-pub ahead of print - 18 Jan 2021


  • John Selden
  • Hugo Grotius
  • Mare Clausum
  • Mare Liberum
  • Dirk Graswinckel
  • Freedom of trade
  • Freedom of fishing
  • Freedom of navigation
  • European international relations
  • early modern diplomacy‌


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