In 2004 Hammes claimed that the world entered a new generation of war, fourth generation warfare. This type of warfare is different from earlier generations since the wars will not be conventional but irregular wars, an advance kind of insurgency. In 2022 the war between Russia and Ukraine suddenly escalates into an undeniable conventional war which puts the relevance of Hammes theory and claim into question. It raises the issue of whether this war disproves the claim and weakens his theory. Whether this war is the return of earlier generations where conventional wars existed or whether there is a possibility that even this war is inherently fourth generational. That the fourth generation generally describes characteristics of warfare today regardless of whether they be conventional or not. The study found that there is an overlap between the criteria Hammes use to define fourth generational conflicts and the war in Ukraine and Russia. This suggests that Hammes theory could still be relevant in this specific case. However, it is also discussed whether the claim can be made that fourth generational warfare truly has replaced its predecessor third generational warfare when there is no real point of comparison between the two generations. Lastly follows a shorter discussion of what this paper contributes with to the military profession and suggestions for further research within this field.