This WWI-vintage poster is a good example of the appeal to national sentiment in time of war. Modern wars are not fought only between opposing armies. Instead, they are fought between entire societies. Therefore, when members of a society believe that they are a nation, that society has a potential advantage. First, belief in the nation can motivate ordinary people to sacrifice ob behalf of the war effort. Similarly, belief in the nation often helps minimize intra-societal conflict, at least initially (this effect tends to wear off over time). It is largely because of the military power of nation states that other states--Japan, for example--sought to create nations out of the peoples under their rule. At first this was a defensive move, but it Japan gradually became an active imperialist power as we will see.