S860 COLUMBIA JOURNAL OF TRANSNATIONAL LAW [56:S855 years. 19 This Section elaborates on the pre-World War I state of international law with respect to nationality. It then discusses the events of World War I that bore on nationality and that ultimately led to changes in States’ nationality practice during the interwar period. It concludes by analyzing State practice, treaties, and discussions thereof to discern how international law changed, and what the implications of nationality were, in the interwar period. A. Pre-World War I State of the Law 1. Regulation in Municipal Law Prior to World War I, the International Law Association (“ILA”) only once discussed, as its focus, the matter of nationality. 20 In 1893, the Sixteenth Annual Conference of the ILA reviewed a three-page report urging the creation of a committee to address international law as it pertained to nationality. The authors of this report worried about the increasing militarization of Europe and how “all and sundry are swept into the armies irrespectively of any considerations of nationality . . . regardless of the fact that an Englishman cannot be turned into a Frenchman, or a Frenchman into a German, by merely putting him into a uniform.” 21 Of particular concern to the authors was the notion of dual nationality, by which young men could be “liable to military service in two States.” 22 The ILA agreed to the appointment of the requested committee, but its committee produced no reports in advance of World War I. From the 1893 report and its brief discussion, it is apparent that municipal law governed the extension of nationality. The substance of nationality, however, bore on matters of international, not local, import and appeared to have common meaning across States. Nationality was viewed as an “allegiance” between a State and its subject, capable of compelling the subject to fight under the banner of the State. 23 19. Nationality Decrees Issued in Tunis and Morocco on November 8th, 1921, Advisory Opinion, 1923 P.C.I.J. (ser. B) No 4, ¶¶ 38–41 (Feb. 7). 20. This was determined through a review of all published ILA conference reports from the inception of the ILA, up to 1913. 21. The Nationality Question, 16 ASS’N REFORM & CODIFICATION L. NATIONS R. CONF. 94, 94 (1893). 22. Id. at 96. 23. Id. Electronic copy available at: https://ssrn.com/abstract=2954729