The desire of the Parties for a natural and visible frontier could have been met by almost any line which followed a recognizable course along the main chain of the Dangrek range. It could have been a crest line, a watershed line or an escarpment line (where an escarpment existed, which was far from always being the case). As will be seen presently, the Parties provided for a watershed line. In so doing, they must be presumed to have realized that such a line would not necessarily, in any particular locality, be the same line as the line of the crest or escarpment. They cannot therefore be presumed to have intended that, wherever an escarpment existed, the frontier must lie along it, irrespective of all other considerations.

The Parties have also relied on other arguments of a physical, historical, religious and archaeological character, but the Court is unable to regard them as legally decisive.

As concerns the burden of proof, it must be pointed out that though, from the formal standpoint, Cambodia is the plaintiff, having instituted the proceedings, Thailand also is a claimant because of the claim which was presented by her in the second Submission of the Counter-Memorial and which relates to the sovereignty over the same piece of territory. Both Cambodia and Thailand base their respective claims on a series of facts and contentions which are asserted or put forward by one Party or the other. The burden of proof in respect of these will of course lie on the Party asserting or putting them forward.

Until Cambodia attained her independence in 1953 she was part of French Indo-China, and her foreign relations - like those of the rest of French Indo-China - were conducted by France as the protecting Power. It is common ground between the Parties that the present dispute has its fons et origo in the boundary settlements made in the period 1904-1908, between France and Siam (as Thailand was then called) and, in particular, that the sovereignty over Preah Vihear depends upon a boundary treaty dated 13 February 1904, and upon events subsequent to that date. The Court is therefore not called upon to go into the situation that existed between the Parties prior to the Treaty of 1904.

The relevant provisions of the Treaty of 13 February 1904, which regulated inter alia the frontier in the eastern Dangrek region, were as follows:

[Translation by the Registry]

"Article 1

The frontier between Siam and Cambodia starts, on the left shore of the Great Lake, from the mouth of the river Stung Roluos, it follows the parallel from that point in an easterly direction until it meets the river Prek Kompong Tiam, then, turning northwards, it merges with the meridian from that meeting-point as far as the Pnom Dang Rek mountain chain. From there it follows the watershed between the basins of the Nam Sen and the Mekong, on the one hand, and the Nam Moun, on the other hand, and joins the Pnom Padang chain the crest of which it follows eastwards as far as the Mekong. Upstream from that point, the Mekong remains the frontier of the Kingdom of Siam, in accordance with Article I of the Treaty of 3 October 1893."

"Article 3

There shall be a delimitation of the frontiers between the Kingdom of Siam and the territories making up French Indo-China. This delimitation will be carried out by Mixed Commissions composed of officers appointed by the two contracting countries. The work will relate to the frontier determined by Articles 1 and 2, and the region lying between the Great Lake and the sea."

It will be seen, in the first place, that these articles make no mention of Preah Vihear as such. It is for this reason that the Court can only give a decision as to the sovereignty over the Temple area after having examined what the frontier line is. Secondly, whereas the general character of the frontier established by Article 1 was, along the Dangrek range, to be a watershed line, the exact course of this frontier was, by virtue of Article 3, to be delimited by a Franco- Siamese Mixed Commission. It is to be observed, moreover, that what had to be delimited was "the frontiers" between Siam and French Indo-China; and although this delimitation had, prima facie, to be carried out by reference to the criterion indicated in Article 1, the purpose of it was to establish the actual line of the frontier. In consequence, the line of the frontier would, to all intents and purposes, be the line resulting from the work of delimitation, unless the delimitation were shown to be invalid.

In due course, a Mixed Commission composed of French and Siamese members was set up, charged with the task of delimiting the frontier in various districts, including the eastern sector of the Dangrek range in which Preah Vihear is situated. This Mixed Commission was composed of two sections, one French and one Siamese, sitting together - one consisting.of French topographical and administrative officers under a French president, and the other of Siamese members under a Siamese president. So far as the frontier in the Dangrek range was concerned, the task of this Mixed Commission was confined to the eastern sector (roughly east of the Pass of Kel) in which Preah Vihear is situated. At this time the western sector of the Dangrek lay wholly in Thailand. It was only when a further boundary settlement, under a treaty dated 23 March 1907, brought within Cambodia various districts abutting on the western Dangrek sector, that the latter became a frontier region. The task of delimiting the frontier in this latter region was given to a second Mixed Commission set up under the 1907 Treaty.

Part 7