Joseph Ryan is an officer in the American Army Air Corps.
Specifically he holds the rank of Colonel and from the history we gain of him, sketchy though it is, he has earned that rank throubh many years of service.
Ryan is described as being "tall and conspicuously erect" with dark blond hair worn "short and bristling" with a "scatter of gray at the temples". He enjoys a deeply tanned complexion except for circles around the eyes normally shielded by sunglasses. "His eyes were finely wrinkled at the corners ... from looking into the sun for enemy fighters". Further, "his was a tough face, grim almost, with no vistige of softness of any kind. It was, from a distance, a young face, but viewed closely was older than its thirty-six years".
What we know of Ryan's life before he arrives at the gates of the Italian prisoner of war camp that forms the basis for our initial interest in him, Ryan had attended the U.S. Military Academy where he "would have graduated second highest academically in his class" if he had not also earned twice as many demerits as the nearest cadet. The young Ryan was a hot-head and a fire-brand, eager to get into a fight and willing to get hurt in order to get a victory.
After six months as an officer, the adventure-demanding Ryan was bored to distraction. The chance of learning to fly helped channel that and his earnest behaviour easily saw him advance in training, certain to gain his wings. He even went so far as to get close to the main instructor and earned a frequent spot at their dinner table, all despite still having his hot-shot attitude. That devil-may-care attitude would have likely continued long into career except one stupid stunt in the air caused an accident that claimed the life of his teacher.
It also destroyed forever the flippancy that Ryan had enjoyed. The Ryan we meet years later is a far different man, one devoted to enforcing the toughest standards of deportment and presentation. It was vital to any who served under him to look and act within the regs because the regulations were there from years of experience as to what worked best and why.
So the Ryan who shows up at the POW camp is absolutely appalled at both the men behind the barbed wire and the staff guarding them. He will make it a point to do something about it. And the strict hard-nosed commander will find once again that while his attitude will earn him the nickname of "Von Ryan" for sometimes taking the side of the guards over the prisoners. That same attitude will also save the lives of many of the men suddenly falling under his command.
The first of two adventures we have of Ryan is largely a military/POW tale. It turns into an espionage tale when in the second half of the adventure he and others dress in enemy uniforms and impersonate the other side. The second tale is even more of one when Ryan must go undercover as a member of the partisans.