The tone is the way the author approaches the subject of a story, a particular scene or piece of writing. A tone of admiration is characterized for having words that show great respect and warm approval toward something or someone. The phrases "highly valuable" and "critical role" help create this tone because they covey how important and decisive was American Indian soldiers' role in defeating the Japanese and bringing the U.S. to victory and the word "courageous" shows respect for the braveness they had in order to endure danger and pain in battle for the U.S.
Look at the words in isolation. What if you were describing any soldier. Would these not be attributes that you would think were quite valuable for any soldier to have.
