Survival is a major theme. Hemingway's war novels depict the harsh reality of trying to stay alive in the midst of battle. The characters are constantly faced with life - or - death situations, which forces them to make difficult decisions. For instance, in 'For Whom the Bell Tolls', the characters must fight for their own survival while also dealing with the moral implications of their actions in a war - torn environment.
The themes of love and disillusionment are common in Ernest Hemingway's war novels. In the context of war, love often becomes a form of solace but also a source of pain. In 'A Farewell to Arms', the love between the protagonist and Catherine is both passionate and doomed. Also, there is a sense of disillusionment with the institutions that promote war. Hemingway shows how the promises of glory and honor in war are often lies, and soldiers are left to deal with the physical and mental scars on their own.
One main theme is the brutality of war. In his novels, Hemingway shows how war strips away the veneer of civilization and exposes the raw, cruel nature of humanity. For example, in 'A Farewell to Arms', the chaos and futility of war are palpable. Another theme is the loss of innocence. The young soldiers go into war full of idealism but come out jaded and broken. And the concept of heroism is also explored. It's not always about grand deeds but often about the small acts of survival and endurance in the face of overwhelming odds.