[Footnote 330: The annexation of the Orange Free State dates from May 24, 1900, and that of the South African Republic from September 1, 1900. It may well be doubted whether at these dates the occupation of the territories concerned was already so complete as to be called effective. The British Government ought not, therefore, to have proclaimed the annexation at such early dates. But there ought to be no doubt that the occupation became effective some time afterwards, in 1901. See, however, Sir Thomas Barclay in _The Law Quarterly Review_, XXI. (1905), p. 307, who asserts the contrary; see also, below, § 264, p. 326, note 2, and § 265, p. 327, note 1. _The Times' History of the War in South Africa_ (vol. V. p. 251) estimates the number of Boer fighters in May 1901 to be about 13,000. These armed men were dispersed into a very large number of guerilla bands, and they were in a great many cases men who seemingly had submitted to the British authorities, but afterwards had taken up arms.] It must be emphasised that the rules regarding effective occupation must be formulated on the basis of actual practice quite as much as rules regarding other matters of International Law. Those rules are not authoritative which are laid down by theorists, but only those which are abstracted from the actual practice of warfare and are unopposed by the Powers.[331] [Footnote 331: The question is so much controverted that it is impossible to enumerate the different opinions. Readers who want to study the question must be referred to the literature quoted above at the commencement of § 166.] [Sidenote: Occupation, when ended.] § 168. Occupation comes to an end when an occupant withdraws from a territory or is driven out of it. Thus, occupation remains only over a limited area of a territory if the forces in occupation are drawn into a fortress on that territory and are there besieged by the re-advancing enemy, or if the occupant concentrates his forces in a certain place of the territory, withdrawing before the re-advancing enemy. But occupation does not cease because the occupant, after having disarmed the inhabitants and having made arrangements for the administration of the country, is marching on to overtake the retreating enemy, leaving only comparatively few soldiers behind. [Sidenote: Rights and Duties in General of the Occupant.]