Ocean Odyssey

A bold and intrepid German sea captain from both world wars had been captured by the American military in 1944, where he was given a choice to help them in their fight against the ferocious army of Imperial Japan or go to prison for life.
Out of the well-being of his crew, his desire to see his family again, and for himself, he takes a dangerous but morally patriotic risk of serving in the US Marines during the brutal island-hopping campaign.
During a major battle where he bravely endured the horrors of infantry combat, he is captured by an all-powerful, mysterious, otherworldly being, and he found himself as a guest in a lost undersea world.
After a bizarre, almost-alien encounter, he is deliberately frozen in time for a thousand years and awakens in a dystopian future world that finds itself in a new conflict.
His new hosts see the heroism and goodness in him, too, and they realized because of his experience, he could lead them in their struggle to defend their new homeland against a sinister force and with that rebuild a proud republic of legend once known in time as America.