The Dutch humanist and jurisconsult Hugo Grotius (1583-1645), now best known for his contributions toward the development of modern international law, spent a significant part of his early career dealing with the affairs of the East Indies, either in the employ of the Dutch East India Company (VOC), or as a negotiator on behalf of the Dutch Republic. 
The present article re-explores a known historical theme and draws attention to Grotius' documents and papers, some of which remain little known or unpublished.  Part I provides an historical account of how the celebrated humanist became involved in issues concerning Dutch commercial and political expansion into Southeast Asia. Part II is specifically dedicated to Grotius' defense of the Sta. Catarina 'incident' of 1603 and places a special focus on its relation to Dutch-Johor co-operation. On the basis of published and unpublished material, a case will be made that the VOC's negotiations with the King of Johor were crucial in stimulating Grotius to formulate his ideas on the issues of sovereignty, trade, just war and alliance-making. In this context a link will be established between the published treatise De Jure Praedae (On the Law of Prize and Booty) and the hitherto unpublished fragment De Societate Publica cum Infidelibus (On Public Society with Non-Christians).  At the same time, the exploration of various issues surrounding trade and affiance-making will serve as an original contribution to the history of Dutch-Johor relations prior to the ratification of a formal alliance in 1606.
Finally, Part III examines how the concepts and ideas originally developed in the context of the Sta. Catarina incident in general, particularly Grotius' justification of Dutch-Johor co-operation, were subsequently reformulated and refined at the Anglo-Dutch Colonial Conferences of 1613 and 1615. These meetings set Anglo-Dutch relations in the Indies on contrasting paths and help explain not only the tension that subsequently arose between the two emerging colonial powers, but also the different policies that they pursued in conducting trade and the process of colonization.
Part I: Grotius, the Seizure of the Sta. Catarina and East India Trade
On 25 February 1603, a large Portuguese-flagged vessel (reportedly 1500 tonnes), the Sta. Catarina, was attacked by the Dutch captain (later Admiral) Jakob van Heemskerk (1567-1607). The incident took place somewhere off the coast of the Johor mainland, probably in the vicinity of present-day Singapore and the mouth of the Johor River.  The Dutch attack continued for most of the day; as evening fell the Sta. Catarina was seriously damaged and had sprung several leaks. The crew accepted surrender on the condition that they be set free. Heemskerk brought all safely to shore, an act for which he was subsequently thanked by the Captain and Governor of Malacca, Fernao d'Albuquerque.
The seizure of the Sta. Catarina became a controversial incident, irritating the Iberian powers over their vulnerability in the Indies, causing some tension in the Dutch alliance with England, and upsetting shareholders of the company over the recourse to (unnecessary) violence.  In fact, however, it was perhaps only symptomatic of the blurred divide between permissible commercial practices and outright piracy. In a decision cast on 9 September 1604, Amsterdam's Admiralty Board recalled the horrible experiences of the Heemskerk expedition and the atrocities previously inflicted on the Dutch by the Portuguese, as well as the latter's crimes and injustices committed against the peoples of the East Indies.  In view of the evidence brought forward in support of the incident the Admiralty Board resolved that the vessel was lawfully seized and its cargo confiscated in an act of war.  Heemskerk thus escaped what in theory, at least, could have amounted to a charge of piracy.
It was about this time (September 1604) that a young (twenty-one year-old) and talented lawyer by the name of Hugo Grotius was asked to write an 'official' account of Heemskerk's actions, though it is not clear what role the VOC might have played or who, precisely, commissioned this work from him. …