Continuous transformation of armed conflict since the adoption in 1864 of the first international humanitarian law treaty compels international humanitarian law to adapt accordingly. These adaptations, through either customary law or new multilateral treaties, always have been towards greater protection, greater reach. As for treaty practice, international humanitarian law historically has been substantially revised every twenty-five to thirty years. This article links those revisions to specific conflicts which laid bare deficiencies in the existing law. What follows is thus a chronicle of conflicts with their most critical humanitarian issues. From this emerges a picture of the changing face of armed conflict since the middle of the nineteenth century. The article also considers recent challenges to international humanitarian law and speculates on possible responses.