Scholars and historians, has any nation won a war they fought exclusively defensively?

[Chili]

15. Russia

In a quick summary, during WWII, Hitler stupidly thought Germany could successfully invade Russia, breaking his non-aggression pact with Stalin. He split the German army and attacked 3 cities at once: Leningrad, Stalingrad, and Moscow. This, while fighting French resistance and bombing England on two fronts. The attacks began in June 1941 - summer. By November, German forces were exhausted, cold, and out of supplies. German troops were devastated by a freezing winter and had to fall back. Hitler had completely underestimated Stalin's army. All he had to do was look at a map, but no. Russia regrouped and captured most of the German army, and pushed them all the way back to Germany.

Not sure if that meets your criteria of being exclusively defensive. But what does seem to meet it - sorta - is the American Revolution. True, American colonies were not a country yet, but they defended the land against the British invasion and won, without being able to attack England in return.