This article examines the changing methods of warfare over the last 100 years, how the law has adapted to respond to these changing methods, and whether the law as it exists in 2014 is still consonant with armed conflict as it exists in 2014. Over the last century, the preponderant type of armed conflict - international armed conflict - has given way to non-international, transnational, and internal armed conflicts. These newly predominant types of armed conflict have also brought with them new participants, new tactics, and new targets. The law of armed conflict has attempted to keep pace with these developments, adopting new comprehensive treaties in 1949 and 1977 (along with a raft of treaties governing permissible means and methods). However, as these new participants employ new or irregular methods to fight their wars, pressures are brought to bear on the existing law of armed conflict. This chapter will use the First World War and its centennial in 2014 as "bookends" with which to frame the discussion of just how wars have changed over the last 100 years, how the law has responded to such changes, and whether the law needs to continue to change in response to altered methods of armed conflict.