Vocabulary

zeal - fervor for a person, cause, or object ; eager desire or endeavor; enthusiastic diligence; ardor.
"Some carried themselves with a sort of wistful resignation, others with pride or stiff soldierly discipline or good humor or macho zeal."(Page 19)
My view to have zeal for something means to have passion for it. To give it all you've got. In my life I have much zeal to be the person God has called me to be. Knowing that he is in control of everything.
One clue that I found when I was reading this was the word "macho". It helped me get a better understanding of what zeal actually meant. To be strong, courageous, and passionate in what you are doing.

tangible - capable of being touched; discernible by the touch; material or substantial.
"they had tangible weight." (page 20)
One tangible item I carry is my Bible. I carry that so I could have an answer to whatever question comes my way,
A clue that I found was when the author wrote "Grief, terror, love, longing-these were intangibles" That helped me realize what tangible meant.

aggression - the action of a state in violating by force the rights of another state, particularly its territorial rights; an unprovoked offensive, attack, invasion, or the like: The army is prepared to stop any foreign aggression.
"A war of national liberation or simple aggression." (Page 38)
Many people in this world have a lot of aggression in their hearts.
A clue that I came across was just reading how the author was talking about the war. For instance he wrote "I was drafted to fight a was I hated." Apparently he has a lot of aggression toward the war.