The idea that warfare has been moving in recent decades into its fourth generation is normally associated with William Lind. It has been taken forward by Thomas Hammes whose article usefully establishes the main features of the thesis. He uses it effectively to explain the failure of the US to appreciate the extent of the resistance it was facing in Iraq and to adjust its tactics accordingly, and makes a compelling case that there are features of the war in Iraq that are shared by other conflicts, past and present. His critique of what has been, at least until now, the dominant mind-set in the Pentagon, is valuable. My concern in this comment is with the underlying concept of fourth generation warfare (4GW). I argue that the activities covered by 4GW are best viewed not as an evolution from earlier, more conventional types of warfare but instead as aspects of a separate process, reflecting strategies that the weak have long adopted in conflicts with superior military powers. These activities, and their interaction with regular forms of warfare, vary considerably in their size and scope, and in the underlying politico-military assumptions that inform them. I conclude that the category of 4GW is too diffuse and the historical analysis upon which it is grounded is weak.