This book addressed the topic of the application of foreign investment protection in times of armed conflict from the perspective of public international law. It looked at the topic from the perspective of multiple fields of public international law and addressed two major issues the present author believed are the most pertinent to ongoing and future investment arbitration cases related to military operations. Given its title, this book focused on protection of foreign investors only. One may argue that in the background of horrors of war and human suffering, foreign businesses are not what governments should be concerned with. But from the point of view of legal doctrine, protection of foreign investments during armed conflict is an interesting topic overarching several areas of public international law, which makes it also quite complex and a challenging object of study. This book sought to contribute to an interesting academic debate developed in recent years by several authors from across the world and humbly contribute to further development of this area. Moreover, the proliferation of investment arbitrations related to claims arising directly out of measures taken during hostilities illustrated the potential of this field of public international law to affect decisions made by State officials (on various levels of governmental hierarchy or military chain of command) during the course of military operations. Eventual restraint on the side of the warring States motivated by the eventual threat of costly investment arbitration may arguably benefit also the civilian population in general (even though circumstances of particular case and alternative decisions taken by the States will only show whether this is really the case).