When reflecting upon the seventeenth and early eighteenth centuries, international relations scholars are likely to recall just a couple of developments: perhaps 1648, the Treaties of Westphalia and the purported dawn of a sovereign state-system in Europe, or perhaps 1713, the Treaty of Utrecht and the rise of balance of power discourse. But arguably, the looming diplomatic preoccupation and font of a voluminous literature in international thought in these years was the question of neutrality, neutral rights, and neutral trade. Lost writings are now surfacing again and receiving careful scholarly attention, and Navigatio Libera by Johann Gröning (first edition 1693, second edition 1698) deserves a central place in a body of work that cannot be neglected if we want to understand the era properly. This fine production of the second edition, with generous expository material and wonderful footnotes, is one to note. The translation has been done meticulously by Peter Maxwell-Stuart, who also provides an essay on Gröning's use of Latin. And there is an indispensable introductory essay by two experts on neutral rights, Leos Müller and Steve Murdoch, which ably places Gröning's book in historico-legal context.

Gröning was born in the North German city of Wismar, on the Baltic Sea, in 1669 and died there in 1747. Wismar joined the Hanseatic League in 1259, and from 1648 to 1803 was a Swedish possession (territory held onto after losing so much in the Great Northern War of 1700–21). Geography was twice destiny. First, Gröning wrote the book to ingratiate himself with the Swedish authorities and obtain a posting as a tribunal referendarius (a sort of high-level legal arbitrator)—an honor he was never granted, though he came to hold two doctorates in law and wrote several other books on legal matters (and numismatism). His topic here is a well-timed, lengthy effort to support the Swedish and Danish insistence that they be able to trade with France unhindered during the Nine Years’ War (1688–97), a position the English and the Dutch were dead set against and had the power to punish.

Second, being a German speaking for Swedes and Danes was a fraught task, and Gröning's first edition attracted criticism, which he rounds upon in a revealing seventeen-page “Essay in His Own Defence” at the beginning of this edition (including Gröning's reproduction of a two-page letter from Samuel von Pufendorf). The Nine Years’ War was most broadly a renewed, Continent-wide, Catholic vs. Protestant struggle, propelled by the efforts of Louis XIV to expand his territory and influence by inflicting himself upon the Dutch and the Holy Roman Empire primarily. Sweden was an avowed rival of Denmark in these years, struggling for control of the Baltic, and it frequently received subsidies from Louis XIV. Sweden linked up with Denmark at the beginning of the war but vacillated regularly; the two did at least agree that they both wanted to profit from the war by trading copiously with both sides. This did not necessarily sit well with Protestants, with Dutch and English commentators, and with many Germans (depending on their links to French money or Catholic power). Gröning is forced to backpedal on his sympathies for James II and apologize to William III, for example.

What were the issues of the time? Most central were disputes over the line between the high seas, where free navigation was felt to rather obviously derive from natural rights, and territorial waters that states could legitimately control. Where did territorial ownership of the sea begin? (The custom of a three-mile limit would soon be established.) Just as controversial was the status and problem of privateering and the fate of seized ships. Gröning supplies myriad historical examples from the previous two hundred years of conflict and copious citations of classics—Hugo Grotius, John Selden, Claude Morisot, Alberico Gentili, Pufendorf, and many others—to make his arguments. He had to walk a tightrope, balancing between Swedish/Danish preferences for enclosed seas for themselves in the Baltic, with general advocacy of trading and shipping rights for neutrals nonetheless. The result is a gem of erudite reflection and argumentation, undeniably of interest to historians of international thought, intellectual history, international law, and the era in question.