The realms of International Law

Kindly write detailed answers to the following three questions of International Law. With proper headings, references, subheadings, and quotations also. 1. Why is it difficult to render accurately a historical account of the origin of International Law? What should be the focus of any account as to how and why International Law began? 2. “A state may exercise its Territorial Jurisdiction once a crime is committed on its territory, regardless where the crime starts or ends.” Discuss 3. “A state that first physically occupies a territory retains sovereignty over it forever.” To what extent is this statement true of the law of acquisition of territory in International Law?