Oppenheim's second edition of International Law. Volume II: War and Neutrality (1912) opens with a preface noting that the text has been increased by one hundred pages, largely due to the inclusion of the thirteen Conventions of the Second Hague Peace Conference and the Declaration of London. The author acknowledges the difficulty of writing a comprehensive treatise when these instruments have not yet been ratified, yet he proceeds to expound them as if they were settled law. This tension between codification and custom runs through the work.

The Author's Method: Revision and Expansion

Oppenheim states that the system of the work remains the same, but portions on Enemy Character, Commencement of War, and Unneutral Service have been entirely rewritten, with new section headings. He adds a whole chapter on the proposed International Prize Court. The preface makes clear that this is not a mere reprint: the author has engaged with recent state practice and scholarly debate. For instance, he discusses whether enemy subjects have persona standi in judicio (§ 100a) and whether trading with enemy subjects is permitted (§ 101). These additions reflect the evolving nature of the law in the early twentieth century.

Asylum on Neutral Territory: A Case-Driven Analysis

In the section on neutral territory as an asylum, Oppenheim grounds his legal principles in concrete historical incidents. He cites the 1558 case of Turkish and Barbary captives who escaped from a Spanish galley wrecked near Calais; France considered them freed by reaching her territory and sent them to Constantinople, despite the Spanish Ambassador's claim. He also references the Franco-German War of 1870, when Belgium detained a French non-commissioned officer who had escaped from German captivity onto Belgian soil. These examples show how Oppenheim uses state practice to illustrate and test legal rules.

The Duty of Impartiality and Territorial Supremacy

Oppenheim emphasizes that a neutral's duty of impartiality does not require refusing asylum to enemy persons or property; rather, the neutral must prevent its territory from being used as a base of hostile operations. He distinguishes between different categories of asylum: for private enemy property, public war material, private subjects, land forces, and naval forces. The discussion is structured around these categories, with cross-references to later sections on naval forces (§§ 342-348). The author's prose is precise, often using conditional clauses to delineate the limits of legal obligations.

Prisoners of War and the Principle of Liberty

A key principle stated is that prisoners of war regain their liberty ipso facto by coming into neutral territory, regardless of how they arrive—whether by escape or by being brought there by enemy troops. Oppenheim notes that this principle has been 'generally recognised for centuries,' but he then raises a nuanced question: does the neutral have a duty to detain such fugitives to prevent them from rejoining the enemy army? He reports that in 1870 Belgium answered in the affirmative, but he does not assert that this is settled law. The careful phrasing leaves room for debate, reflecting the treatise's role as a scholarly exposition rather than a code.

Oppenheim's treatise rewards readers who attend to his use of historical examples and his careful qualification of legal rules. The second edition captures a moment when international law was being reshaped by multilateral conventions, yet customary practice still supplied the essential content. Readers should note the author's habit of stating a general principle and then immediately testing it against state practice or hypothetical cases, a method that makes the work both rigorous and engaging.