Why the reference to checkers in Chapter Three?

The reference to checkers is O'Brien's way of explaining what can be understood and what cannot be understood. Checkers is a game. There are strategies, there's a winner, and there are definite rules. The men, Norman and Henry, embraced the ritualistic challenge it afforded them. The war was an unknown entity. There were pitfalls, and jungles.... people waiting for you around the corner.... no rules, no certainties.