NOTE: I was given early access to this book in exchange for writing an impartial review. Thank you Lake Union Publishing. Scheduled Publication Date: May 4, 2021.

A powerful, often disturbing story of survival during the years surrounding World War II — based on a true story. Awarded four stars on Goodreads.
While not quite as varied a story, in my opinion, as Beneath a Scarlet Sky (also by Mark T. Sullivan) The Last Green Valley remains a compelling story of one family’s struggle under extremely difficult circumstances.
Emil Martel and his wife Adeline are ethnic Germans living in the Ukraine. As the tide in World War II starts to turn against Germany, Nazi officers begin escorting German residents from the Ukraine to Poland, which still remains under German control. Then, of course, that too becomes unsafe.
As the Martels, their children, and their extended families move from place to place — facing difficult travel, inadequate food and lodging, and human brutality — the book completely engulfed me. To the point that I had to take breaks from reading, because of the relentless horror of their lives.
Nevertheless, goodbyes, separations, and deprivation do not shake the dedication of these family members to each other — making the story as inspirational as it is horrific. And recognizing how the Martels represent some 11 million other refugees during the same period put me in awe of what humans can survive.

Photo from his Website
Fortunately, the ending is a happy one. So you can finish the final chapters with a sense of satisfaction. I recommend the book particularly to those who are interested in an aspect of World War II (i.e. German refugees) than is NOT usually featured.
More about the author, Mark T. Sullivan.
More about World War II refugees.
You may also be interested in my review of another Sullivan book, Beneath a Scarlet Sky.