Who is Byron Henry from War and Remembrance and what is their importance?

Byron is the younger son of Pug and Rhoda Henry. He is married to Natalie Jastrow—a Jewess caught in Europe at the beginning of the war. They have one son, Louis, who is also caught in Europe. Byron is serving on a submarine when the United States enters the war. He is in and around where Pug and Warren are at various times, though he also fights many battles far from his family.