In Irene Hunt's Across Five Aprils, what does Jethro think about war?

Caught between the competing visions of the war that is tearing apart his country, Jethro Creighton struggles to reconcile the disparate perspectives to which he has been privy just within his own family. Brother Bill's decision to side with the Confederacy, for instance, makes it impossible for the younger Jethro to demonize that side of the conflict, while the depravity inherent in the practice of slavery makes sympathy for the South a more problematic undertaking.
Like many boys his age (nine when the story begins; thirteen when it ends), Jethro initially conceives of war as an exciting adventure wherein the dangers are stricly hypothetical, but he's smart and perceptive and, exposed to the discussions and debates within his own family, he is exceptionally informed regarding the moral complexities inherent in armed conflicts. That his favorite brother, Bill, will side with the Confederacy while the rest of the family continues to identify with the Union, makes Jethro's internal deliberations all the more compelling. Make no mistake, however, this young boy will experience a fundamental transformation regarding his views of war--a transformation intended to allow Hunt to develop the theme of war as the ultimate, and ultimately futile tragedy. Early in Across Five Aprils, the author notes Jethro's initial excitement at the prospect of war:
"He had listened to his brother Tom and his cousin Eb, the two younger of the grown boys in the household, and their excitement had found its way into his blood."
As the reader learns, however, the realities of war, mainly conveyed to Jethro through letters home from his brothers on the front lines of combat, from the stories he will hear about the horrors of combat from the seriously-wounded Shadrach and from the deserter Eb and, finally from the news of President Lincoln's assassination all faciliate Jethro's dramatic transformation from one who views war as adventure to one who views at as the tragedy that it is.

Sources: