In this scholarly and tightly-argued book, Peter Borschberg re-examines Hugo Grotius's De Iure Praedae (and that part of it that appeared as Mare Liberum in particular), considering why and how the jurist composed the work, what sources he used, and what long-term impact resulted. Grotius is usually assumed to have been a champion of freedom of navigation and access to markets, but Borschberg suggests this image needs considerable qualification. De Iure Praedae was not a product of independent scholarship, having been commissioned by the VOC (Dutch East India Company). Its purpose was to demonstrate that the Dutch seizure in the Johor River estuary in February 1603 of the Portuguese carrack Santa Catarina off Singapore was just and lawful rather than an act of piracy. Fundamental to Grotius's argument was that, because the Portuguese had denied the Dutch their natural right to access Asian markets via the maritime highways, which were open to all and over which no sovereign lawfully exercised lordship, the VOC was entitled to retaliate with force. Moreover, the seizure of the Santa Catarina was demonstrably lawful because the company was acting in support of the king of Johor — an ally with full sovereign rights, who was, at the time, at war with the Portuguese.

As well as finding that De Iure Praedae was a tendentious work, Borschberg concludes that it was based on unacceptably ‘sloppy’ research. This he deduces from careful and telling analysis not only of the text of De Iure Praedae itself, but also of Grotius's seldom-consulted notes and working fragments, which are now in the Leiden University Library. These sources are particularly revealing on how Grotius went about his work. They show that he did not undertake any independent research in the VOC archives. Nor did he have access to any substantial Portuguese sources, relying instead on just a limited range of Spanish material, particularly the writings of the celebrated sixteenth-century theologian and jurist, Francisco de Vitoria of Salamanca — who was, however, writing not about maritime Asia but the quite different situation in Spanish America. As Borschberg clearly demonstrates, Grotius had minimal knowledge and understanding of Portuguese commercial structures in maritime Asia and of the theoretical and legal concepts that underlay them. He knew even less about Malay kingship and ideas of sovereignty, and about Southeast Asian geography.

Yet this is the Grotius who has long occupied a prominent place in the honour roll of seventeenth-century Dutch luminaries and high achievers, alongside the likes of Hals, Huyghens, Rembrandt and Vondel. He had without doubt a brilliant and most versatile mind, and authored an impressive range of theological, historical and juridical works, being especially remembered for his fundamental contribution to the development of international law. But Borschberg's Grotius is as much — or more — an apologist for VOC interests as he is an independent researcher and scholar. Rather than simply championing, without prejudice, genuine freedom of navigation and accessibility to markets, he used his voice to justify the imposition of new Dutch monopolies in place of old Iberian ones. As Malay and other Asian rulers soon discovered, they were required to pay for Dutch protection against the Portuguese with irreversible monopoly trade contracts with the company. When questioned about this at the Anglo-Dutch conferences in 1613 and 1615, Grotius simply explained to the English that the Dutch needed to recoup their expenses, and that these sovereign Asian princes had voluntarily entered into monopoly trade agreements that must be honoured. In this way Grotius effectively supplied a legal and theoretical foundation for the VOC's notorious monopoly — and was therefore ‘one of the early architects of European colonial rule in Asia and beyond’ (p. 168).

Borschberg's book is much enriched by the inclusion of 57 maps and illustrations and over 100 pages of appendices. The appendices comprise mostly a selection of letters, memorials and treatises linked to the Santa Catarina affair, but also include Grotius's own revealing addresses to the 1613 Anglo-Dutch conference, and an excerpt from his ‘Political memoirs’ of 1619. These documents are written variously in Portuguese, Dutch, German and Latin, but English translations are provided. They constitute an invaluable addition to the stock of readily available source material concerning maritime Southeast Asia at the start of an era of momentous change. This book, along with the same author's earlier The Singapore and Melaka Straits (Singapore: NUS Press and KITLV Press, 2010), establishes Borschberg as one of the most significant historians writing today on this key strategic region in the early seventeenth century. It should be warmly welcomed.